Hi, I am going to migrate our existing MySQL5.7 to MariaDB 10.11.9. I setup a new Windows server that installed MySQL 5.7, MariaDB 10.4.34 and MariaDB 10.11.9 without create a new instance. I copied the data directory of MySQL5.7 from existing Windows server to the new server for migration test. First, I am able to start the MySQL5.7 on the new server. Then, I upgrade the MySQL5.7 to MariaDB 10.4.34 successfully using mysql_upgrade_service.exe which under MariaDB 10.4.34 bin directory. But failed at the last step that upgrade MariaDB 10.4.34 to MariaDB 10.11.9 using mariadb-upgrade-service.exe which under MariaDB 10.11.9 bin directory. From the error log, got below message 2024-10-03 16:17:39 0 [Note] InnoDB: Buffer pool(s) load completed at 241003 16:17:39 241003 16:17:40 [ERROR] mysqld got exception 0xc0000005 ; Sorry, we probably made a mistake, and this is a bug. Your assistance in bug reporting will enable us to fix this for the next release. To report this bug, see https://mariadb.com/kb/en/reporting-bugs From the upgrade log, got below message Phase 3/8: Running 'mysql_fix_privilege_tables' ERROR 2017 (HY000): Can't open named pipe to host: . pipe: mysql_upgrade_service_3564 (2) FATAL ERROR: Upgrade failed Checked named pipe enabled and local client able to connect using named pipe at each stage. Any idea why upgrade failed? When upgrade, MariaDB start the instance with socket which is not same as the socket option in my.ini. In this case, it start with socket mysql_upgrade_service_3564; I tried few times the last 4 numeric digits are not fixed and change every time. Thanks.