Why did Personal Vault authentication change?

I suggest opening an issue with OneDrive support. Kind of a PITA but if you work through the automated support items you'll get to a point where you can chat with support.

Contact - Microsoft Support

I have a ticket with OneDrive support and they have been very responsive in communicating with me via email. No closer to a fix at this point than when I started a few days ago - I think if they knew more people were experiencing this issue, it would help escalate the problem. Security is a hot button (rightly!) these days.

I did a full restore on one of my PC's that lost TFA - blew away the C: drive and restored from January 15th, 2023 and got the TFA back - unfortunately this is an extreme step.... I have MS updates turned off for the time being.

As per your suggestion I’ve opened a case with MS. I find that typically wasted time, but I guess if you don’t report it you can’t expect much to happen by way of a solution.

I get the same problem and spent ages trying to figure it out including a complete re-load of the one drive App onto my desktop. Same problem continues. It really undermines confidence in the personal vault security. I want the two part authentication to be the default sign in for personal vault like it was a couple of days ago. MS has changed this without considering its customers. I would like an explanation.

Microsoft sent this reply and closed the case.

Thank you for contacting Microsoft support

I apologies for your experience and I understand how frustrating this can be.  

This error message indicates that the Personal Vault you are trying to access cannot be found on the server. This could be due to a number of reasons, such as the file or directory being removed, the name being changed, or the resource being temporarily unavailable. You can try the following steps to resolve this issue:

 Check if you are using the correct link to access your Personal Vault. Try accessing the Personal Vault from a different device or browser. Wait for a while and try again later, in case the resource is temporarily unavailable. 

I hope this information helps, however if the error persist you can contact Microsoft support on:   https://support.microsoft.com/en-us/contactus/ and for immediate assistance, you may call us at +1-800642-7676(US) 

As best I can see they blew off the actual problem and told me I could contact support which is exactly what generated this response. The person dealing with it clearly didn’t understand the issue, closed the case and sent a generic response. Poor support.

That is disappointing....this is a Microsoft security failure. I would think there should be some way to get attention to this matter. Security issues are prettyhmuch top priority anywhere!!!