I have received this error when upgrading from 21.06.00.012 to 21.11.
The error is
Upgrade to 21.06.00.012 [21:41:34]: Bug 15067 - Add missing languages
ERROR: {UNKNOWN}: DBI Exception: DBD::mysql::db do failed: Duplicate entry
'IN-region' for key 'uniq_lang' at /usr/share/koha/lib/C4/Installer.pm line
738
kindly guide us what to do