After reinstalling my NFS server S (Ubuntu 14.04.5 server which stores the home directory) and client A (Kubuntu 14.04.4 desktop) suddenly Firefox and Thunderbird complain about not being able to find their profiles: "Your firefox profile cannot be loaded. It may be missing or inaccessable."
Concerning Firefox, I checked file permissions, profile.ini, cache locations without succes. I eventually deleted ~/.mozilla to enforce the creation of a new profile, but still get the same error. Obviously, the problem is not introduced by any file from ~/.mozilla.
Firefox and Thunderbird work perfectly on a different NFS client machine B (Kubuntu) which accesses the same NFS server S, using the same directory. I conclude that the problem is created by the machine, not the home dir. On the other hand, a different user can start Firefox without problems even on client A.
Has anybody any idea what could have caused this weird problem?