Error: Timeout (180s) while waiting for lock for transaction log file dovecot.index.log

Hi,

our maildir store is on a NFS share which was working fine for some time with the recommended setting from the dovecot wiki; suddenly today i got informed that one user has login problems to his mails and I have some messages in the logs:

Error: Timeout (180s) while waiting for lock for transaction log file ....../Maildir/dovecot.index.log

My current guess is a hick up in the network during a router configuration this weekend.

My question:

How to solve the problem? I can restart the nfs service/server later this day, as well as the mailserver ... as there is a kernel update too.

Do I have to initiate some resync or deletion of index or whatsoever files?

Thanks for any feedback and regards . Götz