Cannot start Outlook. Cannot open the Outlook window.


Senior Member
Outlook version
Outlook 2010 32 bit
Email Account
Error message:
Cannot start Outlook. Cannot open the Outlook window. The set of folders cannot be opened. The file C:\Users...gmailacct.ost cannot be opened.

Outlook 2013 is being used with an IMAP Gmail account. A month ago this message came up, Outlook would not start. I did the online repair, and it worked ok for a month. Now it is doing it again. I expect that I can reinstall, or maybe create a new profile to fix this. But it seems to me that there may be a Windows issue if it happens twice like this.

Any ideas?

Last edited:

Len Raphael

Senior Member
Outlook version
Outlook 2016 64 bit
Email Account
Office 365 Exchange
Are any windows updates waiting to be installed? That will cause this error.
I've been getting this on various 32 and 64 bit Office 365 machines for a month now. Last part is "An unexpected error has occurred."

Been getting that on different Win 10 pc's with different builds and versions of Office for last several weeks. Some 32 and some 64 Office.

All windows 10 updates applying fine.

Safe mode doesn't help. Deleting profile fixes it for a day to several days. Then problem recurs.

Deleted office credentials.

MS escalation tech working on it is stumped so far.

I'm giving up on Outlook on my main machine and limping along with Win 10 mail I've wasted so much time trying to fix.


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