Strange errors after updating to 2.3.11.3

Hello,

After a recent update, I saw lots of errrors like this:

Oct 05 23:55:35 mail.[redacted] dovecot[1053]: imap(samuel@[redacted])<10580>: Error: Mailbox INBOX: UID=364587: read(zlib(/srv/mail/[redacted]/samuel/mail.mdbox/storage/m.10688)) failed: read(/srv/mail/[redacted]/samuel/mail.mdbox/storage/m.10688) failed: Broken pipe (FETCH BODY[]) Oct 05 23:55:35 mail.[redacted] dovecot[1053]: imap(samuel@[redacted])<10580>: FETCH read() failed in=140 out=1440544 deleted=0 expunged=0 trashed=0 hdr_count=0 hdr_bytes=0 body_count=1 body_bytes=467441

I have been using xz compression for a long time and it has been reliable.

However, the latest update seemed to corrupt some attachments.

So, I downgraded back to:

warning: downgrading package dovecot (2.3.11.3-2 => 2.3.10.1-2) warning: downgrading package pigeonhole (0.5.11-1 => 0.5.10-2)

Now, I see a different error message:

Oct 06 00:13:38 mail.[redacted] dovecot[833]: imap(samuel@[redacted])<4019><efc9ePWwgiOX0qt0>: Error: Corrupted record in index cache file /srv/mail/[redacted]/samuel/mail.mdbox/mailboxes/INBOX/dbox-Mails/dovecot.index.cache: UID 364587: Broken virtual size in mailbox INBOX: read(zlib(/srv/mail/[redacted]/samuel/mail.mdbox/storage/m.10688)): FETCH BODY[] got too little data: 467441 vs 475397

1/ Why did this happen and is there a safe way to upgrade? 2/ Is downgrading a temporary solution? 3/ Are these files lost or can I rebuild them somehow?

Kind regards, Samuel