Cannot start micorosoft outlook

Question

Hi, Keep getting this message and am unable to open outlook.

previously had 2007.

Answer 1

Hello AdamButters,

Based on your description and the screenshot above, my understanding is you are using Outlook on a Windows device, please clarify if I misunderstand your scenario, thanks.

If so, as far as I know we cannot install two kinds of Office suites in the same windows device at the same time.  May I know have you totally uninstalled the Office 2007 ( re-start device required) and then re-install Microsoft 365?  If you have done it but cannot open the new Microsoft 365 Outlook, in this case first please try to run an Office quick repair and then see if the issue disappears. For more details, please refer to Repair an Office application.

Moreover, according to the error message above, it is more likely that the problem is related to the old pst file you are using with Office 2007. To isolate if the problem is that case, please try to run an Outlook data file repair to see if the issue disappears. For your reference Repair Outlook Data Files.

On another hand, if the issue persists after that, I'd like to collect

1. what kind of Outlook ( Office) you are using now, please try to open any other Office apps like Word or Excel and then click File > Account then take a full screenshot here.

2, What kind of email account you are using in Outlook, Microsoft 365 Business email account, outlook.com or some others?

Best Regards,

Oliver