CIFS mount suddenly stopped working error 22

I have been using the following fstab entry on my ubuntu 22.04 client, for mounting a directory on an Ubuntu 20.04 server:

//nas/plex /home/USER/nas/plex cifs uid=0,credentials=/home/USER/somefile,iocharset=utf8,noperm,noauto,user 0 0

Something has changed, and now this no longer works. The error is dmesg is:

[ 3679.254486] CIFS: Attempting to mount \nas\plex[ 3679.259733] CIFS: VFS: cifs_mount failed w/return code = -22

I have tried removing each option separately, but nothing changes.