The OS is Debian GNU/Linux 11
In mailmanweb.log only these two occurrences of the error
ERROR 2023-01-30 13:00:17,375 1078096 hyperkitty.lib.utils Failed to update the fulltext index: (2002, "Can't connect to local MySQL server through socket '/run/mysqld/mysqld.sock' (111)") ERROR 2023-02-22 16:00:02,967 2044909 hyperkitty.lib.utils Failed to update the fulltext index: (2002, "Can't connect to local MySQL server through socket '/run/mysqld/mysqld.sock' (111)")
In uwsgi-error.log they are part of a bigger trace but usually come after a line like which occurs approximately in every 10 minutes
13:17:19 [Q] ERROR reincarnated pusher Process-1:214 after sudden death 13:17:29 [Q] ERROR reincarnated pusher Process-1:215 after sudden death 13:17:40 [Q] ERROR reincarnated pusher Process-1:216 after sudden death 13:17:50 [Q] ERROR reincarnated pusher Process-1:217 after sudden death 13:18:00 [Q] ERROR reincarnated pusher Process-1:218 after sudden death