Julian — that OneDrive message is expected
if the PST file is inside your OneDrive folder.
A
.pst (Outlook data file) is kept
open/locked while Outlook is running, so OneDrive can’t sync it and keeps showing
“This file is in use”. The
real fix is:
don’t store an active PST in OneDrive (it can also cause corruption).
Here’s the simplest way to remove that warning permanently.
Simple fix (recommended): move the PST out of OneDrive
1) Close Outlook completely
- Close Outlook.
- Press Ctrl + Shift + Esc → Task Manager
- End task Microsoft Outlook (OUTLOOK.EXE) if you see it.
2) Create a non‑OneDrive folder
Create this folder: