Passwords no longer work after update from 2.2
I've upgraded an old 2.2 installation to 2.5.6 and all the user passowrds no longer work 🙁.
After a bit of research and looking at the database I see that the passwords are all hashed with the Vanilla method, which in 2.2 uses $P$ (phpass). However in 2.5 the Vanilla method has changed and uses $2y$ (crypt), and it seems it can't automatically rehash the passwords. I've tried instead upgrading to 2.3 first and this works - the passwords are re-hashed to $2a$ on login. However, I really need to update to at least 2.5, so can't upgrade to 2.3 first and wait for all the users (over 2000) to login before then upgrading to 2.5...
Therefore, I think my only option is to change the hash method to 'reset' and force all the users to reset their passwords on their next login.
Has anyone else experienced this, or know of a work-around?