Recently several computers constantly issued an error messages when starting Outlook application. Message text was "An unexpected error has occurred." And after accepting an error with OK button, Outlook app just closed. Loop continues forever, you just could not use Outlook at all. Lot of attempts was made to resolve this issue: starting Outlook in safe mode, Office installation repair, full reinstall. That did not help.
Both computers were Windows 10, one has Microsoft Office Home and Business 2016, other has Office version 2013.The solution in this case for both computers was, creating new Windows users and as as result of course creating new profile structure. Than you have to copy all important files to this new profile back (documents, pictures, bookmarks etc.). Good thing is that most likely when you face this Outlook issue is fresh installed system and you don't have many custom files on computer.
OK, and what was important in my case, you don't just create any user profile, but you try to avoid Unicode characters in profile name (just use Latin ASCII character keyboard set). In my case originally were letters 'ā' and 'ū' in user names, which I changed to 'a' and 'u'.
Anyway it is quite strange that Microsoft in practice still is not supporting Unicode in their software. And looks like it is still better to stay away from "strange" characters in profile folder names. It was English/US versions of both Windows and Office software in my case, might be that localized software versions lacks this problem. Hope this info can help somebody.