You're stuck on a cache error – let's fix it fast
I know that sinking feeling when an app throws 0X00040171 and tells you it's the same cache. It's cryptic, but I've seen it a dozen times, mostly in Outlook or Exchange environments when something's stuck in a loop. The fix is usually quick, but you need to hit the right spot.
Step 1: Clear the cache
First thing – stop whatever app is using that cache. For Outlook, that means closing it completely. Then delete the cache folder. Here's the path for Outlook 2016/2019/365:
%localappdata%\Microsoft\Outlook\Offline Address BooksDelete everything in there. Reopen Outlook – it'll rebuild the cache. I had a client last month whose entire print queue died because a stuck Outlook OST file was hogging the same cache. After clearing this folder, the error vanished.
Step 2: Rebuild the index
If step 1 didn't do it, the cache index itself is corrupted. Open Outlook with the /cleanviews switch. Press Win+R, type:
outlook.exe /cleanviewsThis forces Outlook to rebuild its view cache, which often clears the same cache conflict. For other apps like Windows Search, run:
net stop wsearchThen delete the search index files in C:\ProgramData\Microsoft\Search and restart the service with net start wsearch. The error 0X00040171 usually means the cache thinks it's already loaded but it's corrupt – rebuilding the index resets that.
Why this works
The error translates to “same cache – no action needed” from the Windows error code table. But in real life, it means the cache identifier hasn't changed, so the app thinks it's still got valid data. Trouble is, the cache file is stale or corrupt. Clearing or rebuilding forces the app to generate a new cache identifier. No more conflict.
Less common variations
Sometimes this error shows up in Exchange Server (especially 2013 or 2016) when a database fails to mount. The fix there is running:
eseutil /p /i <path-to-edb>But be careful – that's a repair tool. Back up the database first. Another variation happens in SharePoint for cache profiles. Clear the cache at %ProgramData%\Microsoft\SharePoint. I've also seen it in SQL Server with buffer pool extensions – restarting the SQL service usually clears it.
How to prevent it coming back
Prevention is simple: don't let caches get huge and old. Set Outlook to archive old emails every 90 days. In Exchange, run regular database integrity checks with eseutil /d. For Windows Search, limit indexing to only the folders you need – too many indexed files increases the chance of corruption. Also, update your software. Old Outlook versions (pre-2016) are notorious for cache corruption. Upgrade to 2019 or 365.
That's it. You're back to work.