Older perch website 2.3.2 - can't login

I have had a client email me this morning saying he can't login to his site anymore. After putting in his login details it takes him to the https://www.website.co.uk/frontdoor/core/update/ page

I have tried this with my admin details and the same happens to me also. with the message "Successfully updated to version 2.3.2." and I can't get passed this even after clicking continued.

Any hints on how to resolve this would be appreciated. His website appears to be functioning properly though.