Fatal Error: No matching hash algorithm

We just updated our Expression Engine from version 1.73 to 2.92. Some users, including our system accounts can login fine and some of them get an error “Fatal Error: No matching hash algorithm”.

As we have hundreds of accounts, I need to figure out what exactly is causing certain users to have this issue and which ones aren’t. I’d rather not have all these users reset their passwords (as it would be a lot of communication).

Any clues on what might be going on?