If there are binary logs to be purged at primary server start up within the value of expire_logs_days and slave_connections_needed_for_purge > 0 then the server appears to not purge logs regardless of whether a connecting replica node has processed the event or not. Binlog expiry never occurs after the note is shown.

Steps to replicate:

• Set up replication between two servers
• Create some events on the primary and flush logs

  CREATE DATABASE testing;

  CREATE TABLE testing.t1 (id int);

  INSERT INTO TABLE testing.t1 VALUES(1);

  FLUSH BINARY LOGS;

• Ensure the replica has processed all events on the primary. The binary log file should match the output from show master status on the primary:

  mariadb -e "show all slaves status\G"|grep \ Master_Log_File

• Set binlog_expire_logs_seconds=10 on the primary and restart

At this point the primary should show a similar note in the error log:

2025-02-17 11:23:34 0 [Note] Binary log 'rocky9-MariaDB1-bin.000001' is not purged because less than 'slave_connections_needed_for_purge' slaves have processed it

Binary logs will not ever be expired after this note is shown, though a manual PURGE BINARY LOGS will work.