diff --git a/osu.Game.Tests/Database/BeatmapImporterTests.cs b/osu.Game.Tests/Database/BeatmapImporterTests.cs
index af285f82b1..0546d3e912 100644
--- a/osu.Game.Tests/Database/BeatmapImporterTests.cs
+++ b/osu.Game.Tests/Database/BeatmapImporterTests.cs
@@ -670,6 +670,61 @@ namespace osu.Game.Tests.Database
             });
         }
 
+        [Test]
+        public void TestImportThenReimportWithNewDifficulty()
+        {
+            RunTestWithRealmAsync(async (realm, storage) =>
+            {
+                var importer = new BeatmapImporter(storage, realm);
+                using var store = new RealmRulesetStore(realm, storage);
+
+                string? pathOriginal = TestResources.GetTestBeatmapForImport();
+
+                string pathMissingOneBeatmap = pathOriginal.Replace(".osz", "_missing_difficulty.osz");
+
+                string extractedFolder = $"{pathOriginal}_extracted";
+                Directory.CreateDirectory(extractedFolder);
+
+                try
+                {
+                    using (var zip = ZipArchive.Open(pathOriginal))
+                        zip.WriteToDirectory(extractedFolder);
+
+                    // remove one difficulty before first import
+                    new FileInfo(Directory.GetFiles(extractedFolder, "*.osu").First()).Delete();
+
+                    using (var zip = ZipArchive.Create())
+                    {
+                        zip.AddAllFromDirectory(extractedFolder);
+                        zip.SaveTo(pathMissingOneBeatmap, new ZipWriterOptions(CompressionType.Deflate));
+                    }
+
+                    var firstImport = await importer.Import(new ImportTask(pathMissingOneBeatmap));
+                    Assert.That(firstImport, Is.Not.Null);
+
+                    Assert.That(realm.Realm.All<BeatmapSetInfo>().Where(s => !s.DeletePending), Has.Count.EqualTo(1));
+                    Assert.That(realm.Realm.All<BeatmapSetInfo>().First(s => !s.DeletePending).Beatmaps, Has.Count.EqualTo(11));
+
+                    // Second import matches first but contains one extra .osu file.
+                    var secondImport = await importer.Import(new ImportTask(pathOriginal));
+                    Assert.That(secondImport, Is.Not.Null);
+
+                    Assert.That(realm.Realm.All<BeatmapInfo>(), Has.Count.EqualTo(23));
+                    Assert.That(realm.Realm.All<BeatmapSetInfo>(), Has.Count.EqualTo(2));
+
+                    Assert.That(realm.Realm.All<BeatmapSetInfo>().Where(s => !s.DeletePending), Has.Count.EqualTo(1));
+                    Assert.That(realm.Realm.All<BeatmapSetInfo>().First(s => !s.DeletePending).Beatmaps, Has.Count.EqualTo(12));
+
+                    // check the newly "imported" beatmap is not the original.
+                    Assert.That(firstImport?.ID, Is.Not.EqualTo(secondImport?.ID));
+                }
+                finally
+                {
+                    Directory.Delete(extractedFolder, true);
+                }
+            });
+        }
+
         [Test]
         public void TestImportThenReimportAfterMissingFiles()
         {
@@ -742,7 +797,7 @@ namespace osu.Game.Tests.Database
                 await realm.Realm.WriteAsync(() =>
                 {
                     foreach (var b in imported.Beatmaps)
-                        b.OnlineID = -1;
+                        b.ResetOnlineInfo();
                 });
 
                 deleteBeatmapSet(imported, realm.Realm);
diff --git a/osu.Game.Tests/Database/BeatmapImporterUpdateTests.cs b/osu.Game.Tests/Database/BeatmapImporterUpdateTests.cs
new file mode 100644
index 0000000000..a82386fd51
--- /dev/null
+++ b/osu.Game.Tests/Database/BeatmapImporterUpdateTests.cs
@@ -0,0 +1,447 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using System.Diagnostics;
+using System.IO;
+using System.Linq;
+using System.Linq.Expressions;
+using NUnit.Framework;
+using osu.Framework.Allocation;
+using osu.Game.Beatmaps;
+using osu.Game.Database;
+using osu.Game.Models;
+using osu.Game.Overlays.Notifications;
+using osu.Game.Rulesets;
+using osu.Game.Scoring;
+using osu.Game.Tests.Resources;
+using Realms;
+using SharpCompress.Archives;
+using SharpCompress.Archives.Zip;
+using SharpCompress.Common;
+using SharpCompress.Writers.Zip;
+
+namespace osu.Game.Tests.Database
+{
+    /// <summary>
+    /// Tests the flow where a beatmap is already loaded and an update is applied.
+    /// </summary>
+    [TestFixture]
+    public class BeatmapImporterUpdateTests : RealmTest
+    {
+        private const int count_beatmaps = 12;
+
+        [Test]
+        public void TestNewDifficultyAdded()
+        {
+            RunTestWithRealmAsync(async (realm, storage) =>
+            {
+                var importer = new BeatmapImporter(storage, realm);
+                using var rulesets = new RealmRulesetStore(realm, storage);
+
+                using var __ = getBeatmapArchive(out string pathOriginal);
+                using var _ = getBeatmapArchiveWithModifications(out string pathMissingOneBeatmap, directory =>
+                {
+                    // remove one difficulty before first import
+                    directory.GetFiles("*.osu").First().Delete();
+                });
+
+                var importBeforeUpdate = await importer.Import(new ImportTask(pathMissingOneBeatmap));
+
+                Assert.That(importBeforeUpdate, Is.Not.Null);
+                Debug.Assert(importBeforeUpdate != null);
+
+                checkCount<BeatmapSetInfo>(realm, 1, s => !s.DeletePending);
+                Assert.That(importBeforeUpdate.Value.Beatmaps, Has.Count.EqualTo(count_beatmaps - 1));
+
+                // Second import matches first but contains one extra .osu file.
+                var importAfterUpdate = await importer.ImportAsUpdate(new ProgressNotification(), new ImportTask(pathOriginal), importBeforeUpdate.Value);
+
+                Assert.That(importAfterUpdate, Is.Not.Null);
+                Debug.Assert(importAfterUpdate != null);
+
+                checkCount<BeatmapInfo>(realm, count_beatmaps);
+                checkCount<BeatmapMetadata>(realm, count_beatmaps);
+                checkCount<BeatmapSetInfo>(realm, 1);
+
+                // check the newly "imported" beatmap is not the original.
+                Assert.That(importBeforeUpdate.ID, Is.Not.EqualTo(importAfterUpdate.ID));
+
+                // Previous beatmap set has no beatmaps so will be completely purged on the spot.
+                Assert.That(importBeforeUpdate.Value.IsValid, Is.False);
+            });
+        }
+
+        /// <summary>
+        /// Regression test covering https://github.com/ppy/osu/issues/19369 (import potentially duplicating if original has no <see cref="BeatmapInfo.OnlineID"/>).
+        /// </summary>
+        [Test]
+        public void TestNewDifficultyAddedNoOnlineID()
+        {
+            RunTestWithRealmAsync(async (realm, storage) =>
+            {
+                var importer = new BeatmapImporter(storage, realm);
+                using var rulesets = new RealmRulesetStore(realm, storage);
+
+                using var __ = getBeatmapArchive(out string pathOriginal);
+                using var _ = getBeatmapArchiveWithModifications(out string pathMissingOneBeatmap, directory =>
+                {
+                    // remove one difficulty before first import
+                    directory.GetFiles("*.osu").First().Delete();
+                });
+
+                var importBeforeUpdate = await importer.Import(new ImportTask(pathMissingOneBeatmap));
+
+                Assert.That(importBeforeUpdate, Is.Not.Null);
+                Debug.Assert(importBeforeUpdate != null);
+
+                // This test is the same as TestNewDifficultyAdded except for this block.
+                importBeforeUpdate.PerformWrite(s =>
+                {
+                    s.OnlineID = -1;
+                    foreach (var beatmap in s.Beatmaps)
+                        beatmap.ResetOnlineInfo();
+                });
+
+                checkCount<BeatmapSetInfo>(realm, 1, s => !s.DeletePending);
+                Assert.That(importBeforeUpdate.Value.Beatmaps, Has.Count.EqualTo(count_beatmaps - 1));
+
+                // Second import matches first but contains one extra .osu file.
+                var importAfterUpdate = await importer.ImportAsUpdate(new ProgressNotification(), new ImportTask(pathOriginal), importBeforeUpdate.Value);
+
+                Assert.That(importAfterUpdate, Is.Not.Null);
+                Debug.Assert(importAfterUpdate != null);
+
+                checkCount<BeatmapInfo>(realm, count_beatmaps);
+                checkCount<BeatmapMetadata>(realm, count_beatmaps);
+                checkCount<BeatmapSetInfo>(realm, 1);
+
+                // check the newly "imported" beatmap is not the original.
+                Assert.That(importBeforeUpdate.ID, Is.Not.EqualTo(importAfterUpdate.ID));
+
+                // Previous beatmap set has no beatmaps so will be completely purged on the spot.
+                Assert.That(importBeforeUpdate.Value.IsValid, Is.False);
+            });
+        }
+
+        [Test]
+        public void TestExistingDifficultyModified()
+        {
+            RunTestWithRealmAsync(async (realm, storage) =>
+            {
+                var importer = new BeatmapImporter(storage, realm);
+                using var rulesets = new RealmRulesetStore(realm, storage);
+
+                using var __ = getBeatmapArchive(out string pathOriginal);
+                using var _ = getBeatmapArchiveWithModifications(out string pathModified, directory =>
+                {
+                    // Modify one .osu file with different content.
+                    var firstOsuFile = directory.GetFiles("*.osu").First();
+
+                    string existingContent = File.ReadAllText(firstOsuFile.FullName);
+
+                    File.WriteAllText(firstOsuFile.FullName, existingContent + "\n# I am new content");
+                });
+
+                var importBeforeUpdate = await importer.Import(new ImportTask(pathOriginal));
+
+                Assert.That(importBeforeUpdate, Is.Not.Null);
+                Debug.Assert(importBeforeUpdate != null);
+
+                checkCount<BeatmapSetInfo>(realm, 1, s => !s.DeletePending);
+                Assert.That(importBeforeUpdate.Value.Beatmaps, Has.Count.EqualTo(count_beatmaps));
+
+                // Second import matches first but contains one extra .osu file.
+                var importAfterUpdate = await importer.ImportAsUpdate(new ProgressNotification(), new ImportTask(pathModified), importBeforeUpdate.Value);
+
+                Assert.That(importAfterUpdate, Is.Not.Null);
+                Debug.Assert(importAfterUpdate != null);
+
+                // should only contain the modified beatmap (others purged).
+                Assert.That(importBeforeUpdate.Value.Beatmaps, Has.Count.EqualTo(1));
+                Assert.That(importAfterUpdate.Value.Beatmaps, Has.Count.EqualTo(count_beatmaps));
+
+                checkCount<BeatmapInfo>(realm, count_beatmaps + 1);
+                checkCount<BeatmapMetadata>(realm, count_beatmaps + 1);
+
+                checkCount<BeatmapSetInfo>(realm, 1, s => !s.DeletePending);
+                checkCount<BeatmapSetInfo>(realm, 1, s => s.DeletePending);
+            });
+        }
+
+        [Test]
+        public void TestExistingDifficultyRemoved()
+        {
+            RunTestWithRealmAsync(async (realm, storage) =>
+            {
+                var importer = new BeatmapImporter(storage, realm);
+                using var rulesets = new RealmRulesetStore(realm, storage);
+
+                using var __ = getBeatmapArchive(out string pathOriginal);
+                using var _ = getBeatmapArchiveWithModifications(out string pathMissingOneBeatmap, directory =>
+                {
+                    // remove one difficulty before first import
+                    directory.GetFiles("*.osu").First().Delete();
+                });
+
+                var importBeforeUpdate = await importer.Import(new ImportTask(pathOriginal));
+
+                Assert.That(importBeforeUpdate, Is.Not.Null);
+                Debug.Assert(importBeforeUpdate != null);
+
+                Assert.That(importBeforeUpdate.Value.Beatmaps, Has.Count.EqualTo(count_beatmaps));
+                Assert.That(importBeforeUpdate.Value.Beatmaps.First().OnlineID, Is.GreaterThan(-1));
+
+                // Second import matches first but contains one extra .osu file.
+                var importAfterUpdate = await importer.ImportAsUpdate(new ProgressNotification(), new ImportTask(pathMissingOneBeatmap), importBeforeUpdate.Value);
+
+                Assert.That(importAfterUpdate, Is.Not.Null);
+                Debug.Assert(importAfterUpdate != null);
+
+                checkCount<BeatmapInfo>(realm, count_beatmaps);
+                checkCount<BeatmapMetadata>(realm, count_beatmaps);
+                checkCount<BeatmapSetInfo>(realm, 2);
+
+                // previous set should contain the removed beatmap still.
+                Assert.That(importBeforeUpdate.Value.Beatmaps, Has.Count.EqualTo(1));
+                Assert.That(importBeforeUpdate.Value.Beatmaps.First().OnlineID, Is.EqualTo(-1));
+
+                // Previous beatmap set has no beatmaps so will be completely purged on the spot.
+                Assert.That(importAfterUpdate.Value.Beatmaps, Has.Count.EqualTo(count_beatmaps - 1));
+            });
+        }
+
+        [Test]
+        public void TestUpdatedImportContainsNothing()
+        {
+            RunTestWithRealmAsync(async (realm, storage) =>
+            {
+                var importer = new BeatmapImporter(storage, realm);
+                using var rulesets = new RealmRulesetStore(realm, storage);
+
+                using var __ = getBeatmapArchive(out string pathOriginal);
+                using var _ = getBeatmapArchiveWithModifications(out string pathEmpty, directory =>
+                {
+                    foreach (var file in directory.GetFiles())
+                        file.Delete();
+                });
+
+                var importBeforeUpdate = await importer.Import(new ImportTask(pathOriginal));
+
+                Assert.That(importBeforeUpdate, Is.Not.Null);
+                Debug.Assert(importBeforeUpdate != null);
+
+                var importAfterUpdate = await importer.ImportAsUpdate(new ProgressNotification(), new ImportTask(pathEmpty), importBeforeUpdate.Value);
+                Assert.That(importAfterUpdate, Is.Null);
+
+                checkCount<BeatmapSetInfo>(realm, 1);
+                checkCount<BeatmapInfo>(realm, count_beatmaps);
+                checkCount<BeatmapMetadata>(realm, count_beatmaps);
+
+                Assert.That(importBeforeUpdate.Value.IsValid, Is.True);
+            });
+        }
+
+        [Test]
+        public void TestNoChanges()
+        {
+            RunTestWithRealmAsync(async (realm, storage) =>
+            {
+                var importer = new BeatmapImporter(storage, realm);
+                using var rulesets = new RealmRulesetStore(realm, storage);
+
+                using var __ = getBeatmapArchive(out string pathOriginal);
+                using var _ = getBeatmapArchive(out string pathOriginalSecond);
+
+                var importBeforeUpdate = await importer.Import(new ImportTask(pathOriginal));
+
+                Assert.That(importBeforeUpdate, Is.Not.Null);
+                Debug.Assert(importBeforeUpdate != null);
+
+                var importAfterUpdate = await importer.ImportAsUpdate(new ProgressNotification(), new ImportTask(pathOriginalSecond), importBeforeUpdate.Value);
+
+                Assert.That(importAfterUpdate, Is.Not.Null);
+                Debug.Assert(importAfterUpdate != null);
+
+                checkCount<BeatmapSetInfo>(realm, 1);
+                checkCount<BeatmapInfo>(realm, count_beatmaps);
+                checkCount<BeatmapMetadata>(realm, count_beatmaps);
+
+                Assert.That(importBeforeUpdate.Value.Beatmaps.First().OnlineID, Is.GreaterThan(-1));
+                Assert.That(importBeforeUpdate.ID, Is.EqualTo(importAfterUpdate.ID));
+            });
+        }
+
+        [Test]
+        public void TestScoreTransferredOnUnchanged()
+        {
+            RunTestWithRealmAsync(async (realm, storage) =>
+            {
+                var importer = new BeatmapImporter(storage, realm);
+                using var rulesets = new RealmRulesetStore(realm, storage);
+
+                using var __ = getBeatmapArchive(out string pathOriginal);
+                using var _ = getBeatmapArchiveWithModifications(out string pathMissingOneBeatmap, directory =>
+                {
+                    // arbitrary beatmap removal
+                    directory.GetFiles("*.osu").First().Delete();
+                });
+
+                var importBeforeUpdate = await importer.Import(new ImportTask(pathOriginal));
+
+                Assert.That(importBeforeUpdate, Is.Not.Null);
+                Debug.Assert(importBeforeUpdate != null);
+
+                string scoreTargetBeatmapHash = string.Empty;
+
+                importBeforeUpdate.PerformWrite(s =>
+                {
+                    var beatmapInfo = s.Beatmaps.Last();
+                    scoreTargetBeatmapHash = beatmapInfo.Hash;
+                    s.Realm.Add(new ScoreInfo(beatmapInfo, s.Realm.All<RulesetInfo>().First(), new RealmUser()));
+                });
+
+                checkCount<ScoreInfo>(realm, 1);
+
+                var importAfterUpdate = await importer.ImportAsUpdate(new ProgressNotification(), new ImportTask(pathMissingOneBeatmap), importBeforeUpdate.Value);
+
+                Assert.That(importAfterUpdate, Is.Not.Null);
+                Debug.Assert(importAfterUpdate != null);
+
+                checkCount<BeatmapInfo>(realm, count_beatmaps);
+                checkCount<BeatmapMetadata>(realm, count_beatmaps);
+                checkCount<BeatmapSetInfo>(realm, 2);
+
+                // score is transferred across to the new set
+                checkCount<ScoreInfo>(realm, 1);
+                Assert.That(importAfterUpdate.Value.Beatmaps.First(b => b.Hash == scoreTargetBeatmapHash).Scores, Has.Count.EqualTo(1));
+            });
+        }
+
+        [Test]
+        public void TestScoreLostOnModification()
+        {
+            RunTestWithRealmAsync(async (realm, storage) =>
+            {
+                var importer = new BeatmapImporter(storage, realm);
+                using var rulesets = new RealmRulesetStore(realm, storage);
+
+                using var __ = getBeatmapArchive(out string pathOriginal);
+
+                var importBeforeUpdate = await importer.Import(new ImportTask(pathOriginal));
+
+                Assert.That(importBeforeUpdate, Is.Not.Null);
+                Debug.Assert(importBeforeUpdate != null);
+
+                string? scoreTargetFilename = string.Empty;
+
+                importBeforeUpdate.PerformWrite(s =>
+                {
+                    var beatmapInfo = s.Beatmaps.Last();
+                    scoreTargetFilename = beatmapInfo.File?.Filename;
+                    s.Realm.Add(new ScoreInfo(beatmapInfo, s.Realm.All<RulesetInfo>().First(), new RealmUser()));
+                });
+
+                checkCount<ScoreInfo>(realm, 1);
+
+                using var _ = getBeatmapArchiveWithModifications(out string pathModified, directory =>
+                {
+                    // Modify one .osu file with different content.
+                    var firstOsuFile = directory.GetFiles(scoreTargetFilename).First();
+
+                    string existingContent = File.ReadAllText(firstOsuFile.FullName);
+
+                    File.WriteAllText(firstOsuFile.FullName, existingContent + "\n# I am new content");
+                });
+
+                var importAfterUpdate = await importer.ImportAsUpdate(new ProgressNotification(), new ImportTask(pathModified), importBeforeUpdate.Value);
+
+                Assert.That(importAfterUpdate, Is.Not.Null);
+                Debug.Assert(importAfterUpdate != null);
+
+                checkCount<BeatmapInfo>(realm, count_beatmaps + 1);
+                checkCount<BeatmapMetadata>(realm, count_beatmaps + 1);
+                checkCount<BeatmapSetInfo>(realm, 2);
+
+                // score is not transferred due to modifications.
+                checkCount<ScoreInfo>(realm, 1);
+                Assert.That(importBeforeUpdate.Value.Beatmaps.AsEnumerable().First(b => b.File?.Filename == scoreTargetFilename).Scores, Has.Count.EqualTo(1));
+                Assert.That(importAfterUpdate.Value.Beatmaps.AsEnumerable().First(b => b.File?.Filename == scoreTargetFilename).Scores, Has.Count.EqualTo(0));
+            });
+        }
+
+        [Test]
+        public void TestMetadataTransferred()
+        {
+            RunTestWithRealmAsync(async (realm, storage) =>
+            {
+                var importer = new BeatmapImporter(storage, realm);
+                using var rulesets = new RealmRulesetStore(realm, storage);
+
+                using var __ = getBeatmapArchive(out string pathOriginal);
+                using var _ = getBeatmapArchiveWithModifications(out string pathMissingOneBeatmap, directory =>
+                {
+                    // arbitrary beatmap removal
+                    directory.GetFiles("*.osu").First().Delete();
+                });
+
+                var importBeforeUpdate = await importer.Import(new ImportTask(pathOriginal));
+
+                Assert.That(importBeforeUpdate, Is.Not.Null);
+                Debug.Assert(importBeforeUpdate != null);
+
+                var importAfterUpdate = await importer.ImportAsUpdate(new ProgressNotification(), new ImportTask(pathMissingOneBeatmap), importBeforeUpdate.Value);
+
+                Assert.That(importAfterUpdate, Is.Not.Null);
+                Debug.Assert(importAfterUpdate != null);
+
+                Assert.That(importBeforeUpdate.ID, Is.Not.EqualTo(importAfterUpdate.ID));
+                Assert.That(importBeforeUpdate.Value.DateAdded, Is.EqualTo(importAfterUpdate.Value.DateAdded));
+            });
+        }
+
+        private static void checkCount<T>(RealmAccess realm, int expected, Expression<Func<T, bool>>? condition = null) where T : RealmObject
+        {
+            var query = realm.Realm.All<T>();
+
+            if (condition != null)
+                query = query.Where(condition);
+
+            Assert.That(query, Has.Count.EqualTo(expected));
+        }
+
+        private static IDisposable getBeatmapArchiveWithModifications(out string path, Action<DirectoryInfo> applyModifications)
+        {
+            var cleanup = getBeatmapArchive(out path);
+
+            string extractedFolder = $"{path}_extracted";
+            Directory.CreateDirectory(extractedFolder);
+
+            using (var zip = ZipArchive.Open(path))
+                zip.WriteToDirectory(extractedFolder);
+
+            applyModifications(new DirectoryInfo(extractedFolder));
+
+            File.Delete(path);
+
+            using (var zip = ZipArchive.Create())
+            {
+                zip.AddAllFromDirectory(extractedFolder);
+                zip.SaveTo(path, new ZipWriterOptions(CompressionType.Deflate));
+            }
+
+            Directory.Delete(extractedFolder, true);
+
+            return cleanup;
+        }
+
+        private static IDisposable getBeatmapArchive(out string path, bool quick = true)
+        {
+            string beatmapPath = TestResources.GetTestBeatmapForImport(quick);
+
+            path = beatmapPath;
+
+            return new InvokeOnDisposal(() => File.Delete(beatmapPath));
+        }
+    }
+}
diff --git a/osu.Game.Tests/Visual/Gameplay/TestScenePlayerScoreSubmission.cs b/osu.Game.Tests/Visual/Gameplay/TestScenePlayerScoreSubmission.cs
index 96efca6b65..d1bdfb1dfa 100644
--- a/osu.Game.Tests/Visual/Gameplay/TestScenePlayerScoreSubmission.cs
+++ b/osu.Game.Tests/Visual/Gameplay/TestScenePlayerScoreSubmission.cs
@@ -239,7 +239,7 @@ namespace osu.Game.Tests.Visual.Gameplay
             createPlayerTest(false, r =>
             {
                 var beatmap = createTestBeatmap(r);
-                beatmap.BeatmapInfo.OnlineID = -1;
+                beatmap.BeatmapInfo.ResetOnlineInfo();
                 return beatmap;
             });
 
diff --git a/osu.Game/Beatmaps/BeatmapImporter.cs b/osu.Game/Beatmaps/BeatmapImporter.cs
index 3e4d01a9a3..ef0e76234a 100644
--- a/osu.Game/Beatmaps/BeatmapImporter.cs
+++ b/osu.Game/Beatmaps/BeatmapImporter.cs
@@ -3,9 +3,11 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.IO;
 using System.Linq;
 using System.Threading;
+using System.Threading.Tasks;
 using osu.Framework.Extensions;
 using osu.Framework.Extensions.IEnumerableExtensions;
 using osu.Framework.Logging;
@@ -16,6 +18,7 @@ using osu.Game.Database;
 using osu.Game.Extensions;
 using osu.Game.IO;
 using osu.Game.IO.Archives;
+using osu.Game.Overlays.Notifications;
 using osu.Game.Rulesets;
 using Realms;
 
@@ -38,6 +41,77 @@ namespace osu.Game.Beatmaps
         {
         }
 
+        public override async Task<Live<BeatmapSetInfo>?> ImportAsUpdate(ProgressNotification notification, ImportTask importTask, BeatmapSetInfo original)
+        {
+            var imported = await Import(notification, importTask);
+
+            if (!imported.Any())
+                return null;
+
+            Debug.Assert(imported.Count() == 1);
+
+            var first = imported.First();
+
+            // If there were no changes, ensure we don't accidentally nuke ourselves.
+            if (first.ID == original.ID)
+                return first;
+
+            first.PerformWrite(updated =>
+            {
+                var realm = updated.Realm;
+
+                Logger.Log($"Beatmap \"{updated}\" update completed successfully", LoggingTarget.Database);
+
+                original = realm.Find<BeatmapSetInfo>(original.ID);
+
+                // Generally the import process will do this for us if the OnlineIDs match,
+                // but that isn't a guarantee (ie. if the .osu file doesn't have OnlineIDs populated).
+                original.DeletePending = true;
+
+                // Transfer local values which should be persisted across a beatmap update.
+                updated.DateAdded = original.DateAdded;
+
+                foreach (var beatmap in original.Beatmaps.ToArray())
+                {
+                    var updatedBeatmap = updated.Beatmaps.FirstOrDefault(b => b.Hash == beatmap.Hash);
+
+                    if (updatedBeatmap != null)
+                    {
+                        // If the updated beatmap matches an existing one, transfer any user data across..
+                        if (beatmap.Scores.Any())
+                        {
+                            Logger.Log($"Transferring {beatmap.Scores.Count()} scores for unchanged difficulty \"{beatmap}\"", LoggingTarget.Database);
+
+                            foreach (var score in beatmap.Scores)
+                                score.BeatmapInfo = updatedBeatmap;
+                        }
+
+                        // ..then nuke the old beatmap completely.
+                        // this is done instead of a soft deletion to avoid a user potentially creating weird
+                        // interactions, like restoring the outdated beatmap then updating a second time
+                        // (causing user data to be wiped).
+                        original.Beatmaps.Remove(beatmap);
+
+                        realm.Remove(beatmap.Metadata);
+                        realm.Remove(beatmap);
+                    }
+                    else
+                    {
+                        // If the beatmap differs in the original, leave it in a soft-deleted state but reset online info.
+                        // This caters to the case where a user has made modifications they potentially want to restore,
+                        // but after restoring we want to ensure it can't be used to trigger an update of the beatmap.
+                        beatmap.ResetOnlineInfo();
+                    }
+                }
+
+                // If the original has no beatmaps left, delete the set as well.
+                if (!original.Beatmaps.Any())
+                    realm.Remove(original);
+            });
+
+            return first;
+        }
+
         protected override bool ShouldDeleteArchive(string path) => Path.GetExtension(path).ToLowerInvariant() == ".osz";
 
         protected override void Populate(BeatmapSetInfo beatmapSet, ArchiveReader? archive, Realm realm, CancellationToken cancellationToken = default)
@@ -87,7 +161,7 @@ namespace osu.Game.Beatmaps
                     existingSetWithSameOnlineID.OnlineID = -1;
 
                     foreach (var b in existingSetWithSameOnlineID.Beatmaps)
-                        b.OnlineID = -1;
+                        b.ResetOnlineInfo();
 
                     LogForModel(beatmapSet, $"Found existing beatmap set with same OnlineID ({beatmapSet.OnlineID}). It will be disassociated and marked for deletion.");
                 }
@@ -133,7 +207,7 @@ namespace osu.Game.Beatmaps
                 }
             }
 
-            void resetIds() => beatmapSet.Beatmaps.ForEach(b => b.OnlineID = -1);
+            void resetIds() => beatmapSet.Beatmaps.ForEach(b => b.ResetOnlineInfo());
         }
 
         protected override bool CanSkipImport(BeatmapSetInfo existing, BeatmapSetInfo import)
diff --git a/osu.Game/Beatmaps/BeatmapInfo.cs b/osu.Game/Beatmaps/BeatmapInfo.cs
index 466448d771..66c1995c8b 100644
--- a/osu.Game/Beatmaps/BeatmapInfo.cs
+++ b/osu.Game/Beatmaps/BeatmapInfo.cs
@@ -109,6 +109,17 @@ namespace osu.Game.Beatmaps
         [JsonIgnore]
         public bool Hidden { get; set; }
 
+        /// <summary>
+        /// Reset any fetched online linking information (and history).
+        /// </summary>
+        public void ResetOnlineInfo()
+        {
+            OnlineID = -1;
+            LastOnlineUpdate = null;
+            OnlineMD5Hash = string.Empty;
+            Status = BeatmapOnlineStatus.None;
+        }
+
         #region Properties we may not want persisted (but also maybe no harm?)
 
         public double AudioLeadIn { get; set; }
diff --git a/osu.Game/Beatmaps/BeatmapManager.cs b/osu.Game/Beatmaps/BeatmapManager.cs
index 7717c9cc87..debe4c6829 100644
--- a/osu.Game/Beatmaps/BeatmapManager.cs
+++ b/osu.Game/Beatmaps/BeatmapManager.cs
@@ -164,8 +164,7 @@ namespace osu.Game.Beatmaps
             // clear the hash, as that's what is used to match .osu files with their corresponding realm beatmaps.
             newBeatmapInfo.Hash = string.Empty;
             // clear online properties.
-            newBeatmapInfo.OnlineID = -1;
-            newBeatmapInfo.Status = BeatmapOnlineStatus.None;
+            newBeatmapInfo.ResetOnlineInfo();
 
             return addDifficultyToSet(targetBeatmapSet, newBeatmap, referenceWorkingBeatmap.Skin);
         }
@@ -409,6 +408,9 @@ namespace osu.Game.Beatmaps
             Realm.Run(r => Undelete(r.All<BeatmapSetInfo>().Where(s => s.DeletePending).ToList()));
         }
 
+        public Task<Live<BeatmapSetInfo>?> ImportAsUpdate(ProgressNotification notification, ImportTask importTask, BeatmapSetInfo original) =>
+            beatmapImporter.ImportAsUpdate(notification, importTask, original);
+
         #region Implementation of ICanAcceptFiles
 
         public Task Import(params string[] paths) => beatmapImporter.Import(paths);
diff --git a/osu.Game/Beatmaps/BeatmapOnlineLookupQueue.cs b/osu.Game/Beatmaps/BeatmapOnlineLookupQueue.cs
index d3be240d4c..6a3383cc92 100644
--- a/osu.Game/Beatmaps/BeatmapOnlineLookupQueue.cs
+++ b/osu.Game/Beatmaps/BeatmapOnlineLookupQueue.cs
@@ -88,7 +88,7 @@ namespace osu.Game.Beatmaps
                 if (req.CompletionState == APIRequestCompletionState.Failed)
                 {
                     logForModel(set, $"Online retrieval failed for {beatmapInfo}");
-                    beatmapInfo.OnlineID = -1;
+                    beatmapInfo.ResetOnlineInfo();
                     return;
                 }
 
@@ -118,7 +118,7 @@ namespace osu.Game.Beatmaps
             catch (Exception e)
             {
                 logForModel(set, $"Online retrieval failed for {beatmapInfo} ({e.Message})");
-                beatmapInfo.OnlineID = -1;
+                beatmapInfo.ResetOnlineInfo();
             }
         }
 
diff --git a/osu.Game/Database/IModelImporter.cs b/osu.Game/Database/IModelImporter.cs
index ebb8be39ef..4085f122d0 100644
--- a/osu.Game/Database/IModelImporter.cs
+++ b/osu.Game/Database/IModelImporter.cs
@@ -23,6 +23,16 @@ namespace osu.Game.Database
         /// <returns>The imported models.</returns>
         Task<IEnumerable<Live<TModel>>> Import(ProgressNotification notification, params ImportTask[] tasks);
 
+        /// <summary>
+        /// Process a single import as an update for an existing model.
+        /// This will still run a full import, but perform any post-processing required to make it feel like an update to the user.
+        /// </summary>
+        /// <param name="notification">The notification to update.</param>
+        /// <param name="task">The import task.</param>
+        /// <param name="original">The original model which is being updated.</param>
+        /// <returns>The imported model.</returns>
+        Task<Live<TModel>?> ImportAsUpdate(ProgressNotification notification, ImportTask task, TModel original);
+
         /// <summary>
         /// A user displayable name for the model type associated with this manager.
         /// </summary>
diff --git a/osu.Game/Database/ModelDownloader.cs b/osu.Game/Database/ModelDownloader.cs
index 02bcb342e4..edb8563c65 100644
--- a/osu.Game/Database/ModelDownloader.cs
+++ b/osu.Game/Database/ModelDownloader.cs
@@ -42,7 +42,11 @@ namespace osu.Game.Database
         /// <returns>The request object.</returns>
         protected abstract ArchiveDownloadRequest<T> CreateDownloadRequest(T model, bool minimiseDownloadSize);
 
-        public bool Download(T model, bool minimiseDownloadSize = false)
+        public bool Download(T model, bool minimiseDownloadSize = false) => Download(model, minimiseDownloadSize, null);
+
+        public void DownloadAsUpdate(TModel originalModel) => Download(originalModel, false, originalModel);
+
+        protected bool Download(T model, bool minimiseDownloadSize, TModel? originalModel)
         {
             if (!canDownload(model)) return false;
 
@@ -63,11 +67,15 @@ namespace osu.Game.Database
             {
                 Task.Factory.StartNew(async () =>
                 {
-                    // This gets scheduled back to the update thread, but we want the import to run in the background.
-                    var imported = await importer.Import(notification, new ImportTask(filename)).ConfigureAwait(false);
+                    bool importSuccessful;
+
+                    if (originalModel != null)
+                        importSuccessful = (await importer.ImportAsUpdate(notification, new ImportTask(filename), originalModel)) != null;
+                    else
+                        importSuccessful = (await importer.Import(notification, new ImportTask(filename))).Any();
 
                     // for now a failed import will be marked as a failed download for simplicity.
-                    if (!imported.Any())
+                    if (!importSuccessful)
                         DownloadFailed?.Invoke(request);
 
                     CurrentDownloads.Remove(request);
diff --git a/osu.Game/Database/RealmAccess.cs b/osu.Game/Database/RealmAccess.cs
index 826341a5b9..a93fdea35b 100644
--- a/osu.Game/Database/RealmAccess.cs
+++ b/osu.Game/Database/RealmAccess.cs
@@ -278,7 +278,6 @@ namespace osu.Game.Database
                             realm.Remove(score);
 
                         realm.Remove(beatmap.Metadata);
-
                         realm.Remove(beatmap);
                     }
 
diff --git a/osu.Game/Database/RealmArchiveModelImporter.cs b/osu.Game/Database/RealmArchiveModelImporter.cs
index aa7fac07a8..a0cf98b978 100644
--- a/osu.Game/Database/RealmArchiveModelImporter.cs
+++ b/osu.Game/Database/RealmArchiveModelImporter.cs
@@ -174,6 +174,8 @@ namespace osu.Game.Database
             return imported;
         }
 
+        public virtual Task<Live<TModel>?> ImportAsUpdate(ProgressNotification notification, ImportTask task, TModel original) => throw new NotImplementedException();
+
         /// <summary>
         /// Import one <typeparamref name="TModel"/> from the filesystem and delete the file on success.
         /// Note that this bypasses the UI flow and should only be used for special cases or testing.
diff --git a/osu.Game/Scoring/ScoreManager.cs b/osu.Game/Scoring/ScoreManager.cs
index 7cfc55580b..7367a1ef77 100644
--- a/osu.Game/Scoring/ScoreManager.cs
+++ b/osu.Game/Scoring/ScoreManager.cs
@@ -268,6 +268,8 @@ namespace osu.Game.Scoring
 
         public Task<IEnumerable<Live<ScoreInfo>>> Import(ProgressNotification notification, params ImportTask[] tasks) => scoreImporter.Import(notification, tasks);
 
+        public Task<Live<ScoreInfo>> ImportAsUpdate(ProgressNotification notification, ImportTask task, ScoreInfo original) => scoreImporter.ImportAsUpdate(notification, task, original);
+
         public Live<ScoreInfo> Import(ScoreInfo item, ArchiveReader archive = null, bool batchImport = false, CancellationToken cancellationToken = default) =>
             scoreImporter.ImportModel(item, archive, batchImport, cancellationToken);
 
diff --git a/osu.Game/Screens/Select/Carousel/UpdateBeatmapSetButton.cs b/osu.Game/Screens/Select/Carousel/UpdateBeatmapSetButton.cs
index b80eb40018..73e7d23df0 100644
--- a/osu.Game/Screens/Select/Carousel/UpdateBeatmapSetButton.cs
+++ b/osu.Game/Screens/Select/Carousel/UpdateBeatmapSetButton.cs
@@ -90,7 +90,7 @@ namespace osu.Game.Screens.Select.Carousel
 
             Action = () =>
             {
-                beatmapDownloader.Download(beatmapSetInfo);
+                beatmapDownloader.DownloadAsUpdate(beatmapSetInfo);
                 attachExistingDownload();
             };
         }
diff --git a/osu.Game/Skinning/SkinManager.cs b/osu.Game/Skinning/SkinManager.cs
index dc0197e613..dd35f83434 100644
--- a/osu.Game/Skinning/SkinManager.cs
+++ b/osu.Game/Skinning/SkinManager.cs
@@ -272,6 +272,8 @@ namespace osu.Game.Skinning
 
         public Task<IEnumerable<Live<SkinInfo>>> Import(ProgressNotification notification, params ImportTask[] tasks) => skinImporter.Import(notification, tasks);
 
+        public Task<Live<SkinInfo>> ImportAsUpdate(ProgressNotification notification, ImportTask task, SkinInfo original) => skinImporter.ImportAsUpdate(notification, task, original);
+
         public Task<Live<SkinInfo>> Import(ImportTask task, bool batchImport = false, CancellationToken cancellationToken = default) => skinImporter.Import(task, batchImport, cancellationToken);
 
         #endregion