Re: Re[2]:

=?UTF-8?B?QW5kcmV5IEtseWNoa292?= <aaklychkov@mail.ru> writes:
>> Did you by any chance upgrade the operating system on this server at
>> some point?

> It was installed from Centos 8.1 official iso, then was updated right after installation.

Well, there are two issues here:

1. How did you manage to get duplicate entries into the table?  This
suggests that the existing index is corrupt, else it should have detected
the duplicate.  Peter's question was leading towards one known way that
indexes on text columns can become corrupt.

2. Is reindexdb handling the failure sanely?  While I'd agree that
this behavior isn't especially desirable, it's the price of using
REINDEX CONCURRENTLY.  On failure, you're expected to clean up
manually by removing the leftover invalid index.  Perhaps the
documentation isn't clear enough about that, but I don't see a
bug there.

            regards, tom lane