diff --git a/osu.Game/IO/OsuStorage.cs b/osu.Game/IO/OsuStorage.cs
index 8bcc0941c1..3d6903c56f 100644
--- a/osu.Game/IO/OsuStorage.cs
+++ b/osu.Game/IO/OsuStorage.cs
@@ -2,9 +2,11 @@
 // 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.Threading;
+using JetBrains.Annotations;
 using osu.Framework.Logging;
 using osu.Framework.Platform;
 using osu.Game.Configuration;
@@ -13,12 +15,30 @@ namespace osu.Game.IO
 {
     public class OsuStorage : WrappedStorage
     {
+        /// <summary>
+        /// Indicates the error (if any) that occurred when initialising the custom storage during initial startup.
+        /// </summary>
+        public readonly OsuStorageError Error;
+
+        /// <summary>
+        /// The custom storage path as selected by the user.
+        /// </summary>
+        [CanBeNull]
+        public string CustomStoragePath => storageConfig.Get<string>(StorageConfig.FullPath);
+
+        /// <summary>
+        /// The default storage path to be used if a custom storage path hasn't been selected or is not accessible.
+        /// </summary>
+        [NotNull]
+        public string DefaultStoragePath => defaultStorage.GetFullPath(".");
+
         private readonly GameHost host;
         private readonly StorageConfigManager storageConfig;
+        private readonly Storage defaultStorage;
 
-        internal static readonly string[] IGNORE_DIRECTORIES = { "cache" };
+        public static readonly string[] IGNORE_DIRECTORIES = { "cache" };
 
-        internal static readonly string[] IGNORE_FILES =
+        public static readonly string[] IGNORE_FILES =
         {
             "framework.ini",
             "storage.ini"
@@ -28,23 +48,53 @@ namespace osu.Game.IO
             : base(defaultStorage, string.Empty)
         {
             this.host = host;
+            this.defaultStorage = defaultStorage;
 
             storageConfig = new StorageConfigManager(defaultStorage);
 
-            var customStoragePath = storageConfig.Get<string>(StorageConfig.FullPath);
+            if (!string.IsNullOrEmpty(CustomStoragePath))
+                TryChangeToCustomStorage(out Error);
+        }
 
-            if (!string.IsNullOrEmpty(customStoragePath))
+        /// <summary>
+        /// Resets the custom storage path, changing the target storage to the default location.
+        /// </summary>
+        public void ResetCustomStoragePath()
+        {
+            storageConfig.Set(StorageConfig.FullPath, string.Empty);
+            storageConfig.Save();
+
+            ChangeTargetStorage(defaultStorage);
+        }
+
+        /// <summary>
+        /// Attempts to change to the user's custom storage path.
+        /// </summary>
+        /// <param name="error">The error that occurred.</param>
+        /// <returns>Whether the custom storage path was used successfully. If not, <paramref name="error"/> will be populated with the reason.</returns>
+        public bool TryChangeToCustomStorage(out OsuStorageError error)
+        {
+            Debug.Assert(!string.IsNullOrEmpty(CustomStoragePath));
+
+            error = OsuStorageError.None;
+            Storage lastStorage = UnderlyingStorage;
+
+            try
             {
-                try
-                {
-                    ChangeTargetStorage(host.GetStorage(customStoragePath));
-                }
-                catch (Exception ex)
-                {
-                    Logger.Log($"Couldn't use custom storage path ({customStoragePath}): {ex}. Using default path.", LoggingTarget.Runtime, LogLevel.Error);
-                    ChangeTargetStorage(defaultStorage);
-                }
+                Storage userStorage = host.GetStorage(CustomStoragePath);
+
+                if (!userStorage.GetFiles(".").Any())
+                    error = OsuStorageError.AccessibleButEmpty;
+
+                ChangeTargetStorage(userStorage);
             }
+            catch
+            {
+                error = OsuStorageError.NotAccessible;
+                ChangeTargetStorage(lastStorage);
+            }
+
+            return error == OsuStorageError.None;
         }
 
         protected override void ChangeTargetStorage(Storage newStorage)
@@ -155,4 +205,23 @@ namespace osu.Game.IO
             }
         }
     }
+
+    public enum OsuStorageError
+    {
+        /// <summary>
+        /// No error.
+        /// </summary>
+        None,
+
+        /// <summary>
+        /// Occurs when the target storage directory is accessible but does not already contain game files.
+        /// Only happens when the user changes the storage directory and then moves the files manually or mounts a different device to the same path.
+        /// </summary>
+        AccessibleButEmpty,
+
+        /// <summary>
+        /// Occurs when the target storage directory cannot be accessed at all.
+        /// </summary>
+        NotAccessible,
+    }
 }
diff --git a/osu.Game/Screens/Menu/MainMenu.cs b/osu.Game/Screens/Menu/MainMenu.cs
index 9245df2a7d..c391742c45 100644
--- a/osu.Game/Screens/Menu/MainMenu.cs
+++ b/osu.Game/Screens/Menu/MainMenu.cs
@@ -2,6 +2,7 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System;
+using System.Collections.Generic;
 using System.Linq;
 using osuTK;
 using osuTK.Graphics;
@@ -15,6 +16,7 @@ using osu.Framework.Screens;
 using osu.Game.Configuration;
 using osu.Game.Graphics;
 using osu.Game.Graphics.Containers;
+using osu.Game.IO;
 using osu.Game.Online.API;
 using osu.Game.Overlays;
 using osu.Game.Overlays.Dialog;
@@ -171,6 +173,9 @@ namespace osu.Game.Screens.Menu
             return s;
         }
 
+        [Resolved]
+        private Storage storage { get; set; }
+
         public override void OnEntering(IScreen last)
         {
             base.OnEntering(last);
@@ -187,6 +192,9 @@ namespace osu.Game.Screens.Menu
                     Track.Start();
                 }
             }
+
+            if (storage is OsuStorage osuStorage && osuStorage.Error != OsuStorageError.None)
+                dialogOverlay?.Push(new StorageErrorDialog(osuStorage, osuStorage.Error));
         }
 
         private bool exitConfirmed;
@@ -308,5 +316,76 @@ namespace osu.Game.Screens.Menu
                 };
             }
         }
+
+        private class StorageErrorDialog : PopupDialog
+        {
+            [Resolved]
+            private DialogOverlay dialogOverlay { get; set; }
+
+            [Resolved]
+            private OsuGameBase osuGame { get; set; }
+
+            public StorageErrorDialog(OsuStorage storage, OsuStorageError error)
+            {
+                HeaderText = "osu! storage error";
+                Icon = FontAwesome.Solid.ExclamationTriangle;
+
+                var buttons = new List<PopupDialogButton>();
+
+                BodyText = $"osu! encountered an error when trying to use the custom storage path ('{storage.CustomStoragePath}').\n\n";
+
+                switch (error)
+                {
+                    case OsuStorageError.NotAccessible:
+                        BodyText += $"The default storage path ('{storage.DefaultStoragePath}') is currently being used because the custom storage path is not accessible.\n\n"
+                                    + "Is it on a removable device that is not currently connected?";
+
+                        buttons.AddRange(new PopupDialogButton[]
+                        {
+                            new PopupDialogOkButton
+                            {
+                                Text = "Try again",
+                                Action = () =>
+                                {
+                                    if (!storage.TryChangeToCustomStorage(out var nextError))
+                                        dialogOverlay.Push(new StorageErrorDialog(storage, nextError));
+                                }
+                            },
+                            new PopupDialogOkButton
+                            {
+                                Text = "Use the default path from now on",
+                                Action = storage.ResetCustomStoragePath
+                            },
+                            new PopupDialogCancelButton
+                            {
+                                Text = "Only use the default path for this session",
+                            },
+                        });
+                        break;
+
+                    case OsuStorageError.AccessibleButEmpty:
+                        BodyText += "The custom storage path is currently being used but is empty.\n\n"
+                                    + "Have you moved the files elsewhere?";
+
+                        // Todo: Provide the option to search for the files similar to migration.
+                        buttons.AddRange(new PopupDialogButton[]
+                        {
+                            new PopupDialogOkButton
+                            {
+                                Text = "Reset to default",
+                                Action = storage.ResetCustomStoragePath
+                            },
+                            new PopupDialogCancelButton
+                            {
+                                Text = "Keep using the custom path"
+                            }
+                        });
+
+                        break;
+                }
+
+                Buttons = buttons;
+            }
+        }
     }
 }