dovecot: Bad file descriptor

Hello *,

I've been noticing a large number of error messages in the maillog
coming from dovecot.

There seems to be a problem yet unknown problem. I've been running this
setup now for a few years and never had problems like these.

$ cat /var/log/maillog

Jun  6 18:13:06 stg-00 dovecot:
imap(list@md5collisions.eu)<20289><1lU4KhvECr4KAgBk>: Error: kevent(-1)
for notify remove failed: Bad file descriptor
Jun  6 18:13:06 stg-00 dovecot:
imap(list@md5collisions.eu)<20289><1lU4KhvECr4KAgBk>: Error: close(-1)
for notify remove failed: Bad file descriptor
Jun  6 18:13:06 stg-00 dovecot:
imap(list@md5collisions.eu)<20289><1lU4KhvECr4KAgBk>: Error: kevent(-1)
for notify remove failed: Bad file descriptor
Jun  6 18:13:06 stg-00 dovecot:
imap(list@md5collisions.eu)<20289><1lU4KhvECr4KAgBk>: Error: close(-1)
for notify remove failed: Bad file descriptor
Jun  6 18:13:06 stg-00 dovecot:
imap(list@md5collisions.eu)<20289><1lU4KhvECr4KAgBk>: Error: Couldn't
hibernate imap client: fd_send(/var/dovecot/imap-hibernate) failed:
Invalid argument


Do you guys have any idea, whats the matter?


Best regards,

Stephan