Resolved Mail not accessible after upgrade to 17.5

[TorbHo]

After the upgrade to 17.5 Dovecot and Postfix seem to work, but I can't reach the mail configuration via Plesk interface.
Error Message: access denied

I tried plesk repair all and plesk repair installation.

plesk repair all does not find an error and plesk repair installation aborts with the error:

Bootstrapper repair finished.
Errors occurred while performing the following actions: restore mail.
Check '/var/log/plesk/install/plesk_17.5.3_repair.log' and '/var/log/plesk/install/plesk_17.5.3_repair_problems.log' for details.
If you can't resolve the issue on your own, please address Parallels support.

The mchk.log shows:

fail
Errors occured in mail restore procedure
Some utilities have exited with errors:
  /usr/lib/plesk-9.0/remote_mail_restore/mail_auth_dump
  /usr/lib/plesk-9.0/remote_mail_restore/mail_imap_restore
  /usr/lib/plesk-9.0/remote_mail_restore/mail_outgoing_restore
  /usr/lib/plesk-9.0/remote_mail_restore/mail_transport_restore
STOP Mail restore (/usr/lib/plesk-9.0/mail_restore --with-spam) AT Thu May  4 07:00:37 CEST 2017

What can I do?

 

[TorbHo]

As described above: Plesk repair did not work. Now I tried "apt-get update && apt-get upgrade".

This seemed to fix everything.