Mailbox access error on Plesk for Linux: Panic: file mail-index-sync-keywords.c: assertion failed

Symptoms

• A mailbox was migrated from cPanel to Plesk.

• Inbox or Sent folders can be empty, but mails exist on the server.

• The following error may be displayed in the Thunderbird mail client

• The following errors may appear in the /var/log/maillog file in an attempt to access mailbox via Thunderbird, send an email to the Plesk server, or when accessing a specific directory in the mailbox:

  server dovecot: service=imap, user=johndoe@example.com, ip=[203.0.113.2]. Panic: file mail-index-sync-keywords.c: line 228 (keywords_update_records): assertion failed: (data_offset >= sizeof(struct mail_index_record))
  server dovecot: service=imap, user=johndoe@example.com, ip=[203.0.113.2]. Error: Raw backtrace:
  ...

  ---

  hostname dovecot: service=imap, user=johndoe@example.com, ip=[127.0.0.1]. Fatal: master: service(imap): child 24963 killed with signal 6

  ---

  hostname dovecot: service=imap, user=johndoe@example.com, ip=[127.0.0.1]. Error: Corrupted record in index cache file /var/qmail/mailnames/example.com/johndoe/Maildir/dovecot.index.cache: UID 70: Broken physical size in mailbox INBOX

  ---

  Error: Mailbox INBOX: UID=68: read(/var/qmail/mailnames/example.com/johndoe/Maildir/cur/1323171020.15581.example.com,S=7620:2,RS) failed: Cached message size smaller than expected (7620 < 7660, box=INBOX, UID=68) (read reason=)

• The following error could be displayed on a side of the Thunderbird mailclient.

  The STAT command did not succeed. Error getting message number and sizes. Mail server ns1.pleskserver22.nl responded: [SYS/TEMP] external error occurred. Refer to server log for more information.

Cause

Corrupted Dovecot index file.

Resolution

1. Connect to the server via SSH.

2. Rename the /var/qmail/mailnames/example.com/johndoe/Maildir/dovecot.index file:

   # mv /var/qmail/mailnames/example.com/johndoe/Maildir/dovecot.index /var/qmail/mailnames/example.com/johndoe/Maildir/dovecot.index.back

3. Move the dovecot.index file in the directory to which the access is not possible or folder is empty e.g. "Sent":

   # mv /var/qmail/mailnames/example.com/johndoe/Maildir/.Sent/dovecot.index /var/qmail/mailnames/example.com/johndoe/Maildir/.Sent/dovecot.index.back

4. Access the mailbox via webmail to regenerate the dovecot.index files.