How to move AppData folder to another drive on Windows

Some applications write gigabytes of cache, logs, and profile data to C:\Users\John\AppData — with no built-in option to change that location. On systems with a small SSD boot drive, this fills up quickly. The standard solution is to move the target folder to a secondary drive and replace it with a junction that points back to the new location. The application continues to write to the original path and never notices anything changed.

This article uses Firefox as the example. Firefox stores its full profile — bookmarks, extensions, cache, session data — in AppData\Roaming\Mozilla\Firefox\Profiles\ and can easily reach 1–2 GB on an active workstation. The procedure applies to any application that writes to AppData.

Prerequisites

Windows 10 or Windows 11
A secondary drive with sufficient free space — this guide uses D:\, adjust to your drive letter
Administrator access
Firefox must be fully closed before you start — including any background update processes

Warning: Do not attempt this procedure while Firefox is running. Open file handles on the profile folder will prevent robocopy from completing cleanly and may result in a corrupted or partially moved profile.

Step-by-step procedure

Step 1 — Find your Firefox profile folder

Firefox stores each user profile in a subfolder with a randomly generated name inside AppData\Roaming\Mozilla\Firefox\Profiles\. The subfolder name looks like ab12cd34.default-release — you need to find the exact name on your machine before running any commands.

Press Win + R, type the following path and press Enter:

%AppData%\Mozilla\Firefox\Profiles

File Explorer opens directly at the Profiles folder. You will see one or more subfolders. The active profile is the one named xxxxxxxx.default-release.

Note: If you see multiple profile folders, open Firefox, go to about:profiles in the address bar, and look for the profile marked This is the profile in use. The Root Directory path shown there tells you which folder is active.

Step 2 — Close Firefox completely

Close Firefox. Then open Task Manager (Ctrl + Shift + Esc) and confirm no Firefox processes remain running — look for firefox.exe in the Processes tab. End any remaining processes before continuing.

Step 3 — Open an elevated Command Prompt

Press Win, type cmd, right-click Command Prompt and select Run as administrator. All commands in the following steps must be run in this elevated window.

Step 4 — Create the destination folder on D:\

Create the folder structure on the secondary drive where the Firefox profile will be stored.

mkdir "D:\AppData\Mozilla\Firefox"

Note: If any part of this path already exists, the command returns an error — that is fine, the existing folders are kept and you can proceed.

Step 5 — Copy the Profiles folder to D:\ using robocopy

Use robocopy to copy the entire Firefox Profiles folder to the new location. We copy the Firefox parent folder so the destination structure mirrors the source exactly — D:\AppData\Mozilla\Firefox\Profiles\ will contain all profile subfolders.

robocopy "C:\Users\John\AppData\Roaming\Mozilla\Firefox" "D:\AppData\Mozilla\Firefox" /E /COPYALL /R:3 /W:5

Flag	What it does
`/E`	Copy all subdirectories, including empty ones
`/COPYALL`	Preserve all file attributes, timestamps, and permissions
`/R:3`	Retry failed files up to 3 times
`/W:5`	Wait 5 seconds between retries

When robocopy finishes it prints a summary table. Wait for it to complete before proceeding.

Result: The Firefox Profiles folder is now present at D:\AppData\Mozilla\Firefox\Profiles. The original folder on C:\ still exists — do not delete it yet.

Step 6 — Verify the copy is complete

Before removing the original, confirm that the file count and total size match exactly between source and destination.

:: Check the original Firefox folder
dir "C:\Users\John\AppData\Roaming\Mozilla\Firefox" /S | find "File(s)"

:: Check the new location on D:\
dir "D:\AppData\Mozilla\Firefox" /S | find "File(s)"

Both commands should return identical output. Example:

       3204 File(s)    1,204,847,360 bytes
       3204 File(s)    1,204,847,360 bytes

Warning: Do not proceed to Step 7 until both the file count and byte count match exactly. If they differ, run the robocopy command from Step 5 again — it will copy only the missing or changed files.

Step 7 — Delete the original Profiles folder

Once the copy is confirmed complete, remove only the Profiles subfolder from C:\. We keep the Firefox parent folder intact — it contains profiles.ini, a configuration file that Firefox uses to locate its profiles. Removing it would break Firefox on next launch.

rd /S /Q "C:\Users\John\AppData\Roaming\Mozilla\Firefox\Profiles"

Common mistake: Running this command before verifying Step 6. If robocopy did not finish successfully and you delete the source, the missing files are permanently gone. Always verify the copy first.

Step 8 — Create the junction

Create a junction at the original Profiles path pointing to the new location on D:\. Firefox will follow this path exactly as before — profiles.ini on C:\ remains in place and continues to work normally.

mklink /J "C:\Users\John\AppData\Roaming\Mozilla\Firefox\Profiles" "D:\AppData\Mozilla\Firefox\Profiles"

CMD confirms the junction was created:

Junction created for C:\Users\John\AppData\Roaming\Mozilla\Firefox\Profiles <<===>> D:\AppData\Mozilla\Firefox\Profiles

Result: The junction is in place. C:\Users\John\AppData\Roaming\Mozilla\Firefox\Profiles now redirects transparently to D:\AppData\Mozilla\Firefox\Profiles.

Step 9 — Verify the junction

Confirm the junction is correctly in place and points to the right target.

dir /AL "C:\Users\John\AppData\Roaming\Mozilla\Firefox"

Expected output:

25/03/2026  11:30    <JUNCTION>     Profiles [D:\AppData\Mozilla\Firefox\Profiles]

The <JUNCTION> tag confirms this is a link, not a real folder. The path in brackets is the target — verify it points exactly to D:\AppData\Mozilla\Firefox\Profiles.

Step 10 — Test Firefox

Launch Firefox. It should open normally, load your profile, restore your tabs, and show all bookmarks and extensions as before. If Firefox opens correctly with your profile intact, the junction is working.

To confirm data is writing to the secondary drive, open D:\AppData\Mozilla\Firefox\Profiles in File Explorer after a few minutes of browsing — file timestamps inside should be updating.

Result: Firefox runs normally with your full profile. All new data — cache, session files, cookies — is written to D:\. The C:\ drive no longer accumulates Firefox profile data.

Common problems

Problem	Cause	Fix
robocopy reports Access denied on some files	Firefox or a background update process is still running	Open Task Manager, end all `firefox.exe` and `updater.exe` processes, then retry
mklink fails: Cannot create a file when that file already exists	Step 7 was skipped — the original Profiles folder was not deleted	Run `dir "C:\Users\John\AppData\Roaming\Mozilla\Firefox"` to confirm Profiles is gone, then re-run mklink
Firefox opens with a blank profile after the junction	The junction points to a wrong or empty target path	Run `dir /AL "C:\Users\John\AppData\Roaming\Mozilla\Firefox"` and verify the Profiles entry shows `<JUNCTION>` with the correct target
Firefox fails to start with a profile error	Folder permissions were not preserved during robocopy	Right-click `D:\AppData\Mozilla\Firefox\Profiles` → Properties → Security → confirm your user account has Full Control

Notes

Why junction and not a symbolic link

This procedure uses mklink /J (junction) rather than mklink /D (directory symbolic link). Junctions are more reliable for user profile paths because some Windows components and application installers do not correctly follow symbolic links inside AppData. Junctions use the NTFS mount point mechanism which has broader system-level support.

Moving the cache separately

Firefox also stores a separate cache in AppData\Local\Mozilla\Firefox\Profiles. This folder is often larger than the Roaming profile and regenerates automatically if deleted. You can apply the same procedure to move it to D:\ independently — or simply delete it and let Firefox rebuild it on next launch.

How to revert the change

Close Firefox. Remove the junction with rd "C:\Users\John\AppData\Roaming\Mozilla\Firefox\Profiles" — no /S flag, this removes only the link without touching D:\. Then use robocopy to move the Profiles folder back from D:\AppData\Mozilla\Firefox\Profiles to C:\Users\John\AppData\Roaming\Mozilla\Firefox\Profiles.

Official reference

mklink — Windows Commands | Microsoft Learn

robocopy — Windows Commands | Microsoft Learn