File Explorer caches every thumbnail it has ever rendered in %localappdata%\Microsoft\Windows\Explorer. On a PC with heavy photo and video folders, this cache easily grows past 1 GB, and corruption in it is why Explorer sometimes shows stale or blank thumbnails.
Short answer: open Disk Cleanup (cleanmgr), tick Thumbnails, and click OK. To force Explorer to regenerate from scratch, stop explorer.exe first, delete every thumbcache_*.db file, and restart Explorer.
The gentle path — Disk Cleanup
- press Start, type
cleanmgr, press Enter - choose drive C:, click OK
- wait for the scan
- tick Thumbnails (leave Temporary files and Recycle Bin ticked too if you want)
- click OK > Delete Files
Disk Cleanup handles the cache files safely without needing to restart Explorer.
The forced path — manually deleting thumbcache_*.db
Use this when Disk Cleanup finishes but thumbnails still misbehave (wrong image, blank icons, crashes).
- open Task Manager (Ctrl + Shift + Esc)
- find Windows Explorer, right-click > End task
- the taskbar disappears — do not panic
- press Ctrl + Shift + Esc again to keep Task Manager open
- click File > Run new task, type
cmd, tick Create this task with administrative privileges, click OK - in the Command Prompt, run:
cd /d %localappdata%\Microsoft\Windows\Explorerdel /f /q thumbcache_*.dbdel /f /q iconcache_*.db
- in Task Manager, File > Run new task, type
explorer.exe, click OK - the taskbar returns
Next time you browse a folder, Windows rebuilds the thumbnail cache fresh.
Preventing cache bloat
- Settings > System > Storage > Storage Sense, toggle On — Storage Sense clears thumbnails on its schedule
- avoid setting File Explorer to Extra large icons on folders with thousands of media files — the cache balloons to match
Better next routes
For the broader Windows cleanup, continue with How to Free Up Space on C Drive Windows 11 Natively.
For the cross-platform catch-all, read Storage Space Running Out: How to Check What's Taking Up Space.