I have been dealing with this situation now for the past week or more and QB hasn't provided any support.
I have both an Investigation # and a Case # related to this issue.
QB Online
Account & Settings / Advanced - the screen freezes and won't let me change the month-end closing date.
Based on the facts that I have provided the following items are now known:
The issue is not my computer
The issue is not the browser because I have tried 3 browsers as well as Incognito and all 3 have resulted in the same error
The Cache was cleared so this is not the issue
The issue is not the User (me) because I was able to successfully make the month-end close for the past 2 months and I can do the month-end close for another company we have without any problem.
I have suggested that the only other alternative at this time is that there might be a problem with the Company Data File and asked that it be repaired, but nobody at QB will address my suggestion.
I have already submitted the Feb 2023 F/S to the Owner, and I need to change the close date to 02/28/2023 to prevent the staff from inadvertently posting transactions back into February.