Outlook Won't Open
Outlook either doesn't open at all, shows an error immediately, hangs on a loading screen, or crashes shortly after opening.
Quick answer: Outlook failing to open is most often a corrupted profile or a damaged add-in, rather than anything wrong with your actual email account. Starting Outlook in Safe Mode (hold Ctrl while opening it) is the quickest way to tell whether an add-in is the cause.
Likely causes
- A corrupted Outlook profile
- A problematic add-in loading at startup
- A corrupted data file (particularly with older .pst-based setups)
- A conflict introduced by a recent Windows or Office update
What you can safely check yourself
- Hold Ctrl while clicking the Outlook icon to start in Safe Mode, which disables add-ins — if it opens fine this way, an add-in is likely the cause
- Check for pending Windows or Microsoft 365 updates and install them
- Restart the computer, which resolves a surprising number of one-off Outlook hangs
Don't delete or recreate your Outlook profile as a first step if you have offline/cached email you'd lose access to — check what's actually stored locally versus on the mail server first.
When it needs a proper look
If Safe Mode doesn't help and updates don't resolve it, the profile itself likely needs rebuilding — worth getting help with to avoid losing local data in the process.