How do I fix this - "Something went wrong [1001]"

For everyone that is still experiencing this issue, Ian Shearman's response on this post fixed the issue for me (although I'm sure it will come back again in the next couple of weeks)... it's good fix while a solution continues to be investigated.

https://learn.microsoft.com/en-us/answers/questions/1144046/outlook-365-application-error-1001-mail-is-not-syn

1. Close all Microsoft applications, office, teams etc.
2. Go to your AppData folder and navigate to Microsoft (C:\Users*yourusername*\AppData\Local\Microsoft)
3. Cut/paste the OneAuth and IdentityCache folders out of the Microsoft folder and paste it onto your desktop.
4. Relaunch Outlook and sign in. It might already be fixed at this point. If not, close out of Outlook, copy the OneAuth and IdentityCache folders back into the Microsoft AppData folder but.. when it asks if you want to overwrite, say NO.
5. Relaunch Outlook and sign in, should be working now.

So basically "If not, you can use web version of your products." is the only solution? Geez. Helpful? NOT!

I am 82 and I can't do the things suggested. Am at the end of the rope and sliding fast. Some nice girl from microsoft helped me until 12:30 A.M. Problem is still there. It will not let me sign in to M365. Error 1001. Have not been able to use 365 for weeks. Frustrated. If there is an easy fix for an old person hope someone puts something on here. 365 was taken off twice and put back on. Everything was up to date.

I went around in circles to figure this out. My fix was to place two services on Automatic and then restarted them. They were the "Microsoft Account Sign-In Assistant" and "Web Account Manager". As soon as I did this, my name appeared on the Excel and Word headers, where previously it would only say "Sign In". So, I just ignored the error screen and all was good.

Dear BDrais,

Good day!!

I understand your concern and I would like to let you know that I have checked the service health dashboard at the Microsoft end and there is no any incident related to it.

In this situation, I would like to suggest you check whether the Office apps are updated to the latest version. Open any Office app such as Word> Account> Update Options> Update now.

If the Office apps are up to date, then please reset your Office apps activation state and reactivate them to check the outcome. Reference: Reset activation state for Microsoft 365 Apps for enterprise - Office | Microsoft Learn (Method: Use scripts to automate the cleanup process)

After resetting the Office apps> Restart your device> Open the Office apps> Sign in with your Office 365 account> Open> SharePoint> Go to location of the file and double-click on it to open.

If the problem persists, can you please check whether other users in your organization are having the same issue?

Sorry for the inconvenience caused and thanks for your patience.

Best Regards,

Sophia