Redmine

If I'm not wrong, Ubuntu 22.04 ships MariaDB version 10.5.12 and according to the docs, the variable name in versions before 11.1.1 is tx_isolation. Can you try with this?

To determine the global and session transaction isolation levels at runtime, check the value of the tx_isolation system variable (note that the variable has been renamed transaction_isolation from MariaDB 11.1.1, to match the option, and the old name deprecated).

Thanks for the suggestion. I'm using Ubuntu 24.04, not 22.04. MariaDB is "Ver 15.1 Distrib 10.11.7-MariaDB".

I have searched, but can't find where "transaction_isolation" appears in the part of the installation of Redmine that fails, so I don't know how to replace it with tx_isolation.

I fixed the 'transaction_isolation' problem by upgrading to MariaDB 11.3.2 using the binary tarballs from mariadb.com.

'tx_isolation: "READ-COMMITTED"' in database.yml does the job when using MariaDB 10.11.6 (Debian Bookworm).
I also also had to insert 'transaction-isolation=READ-COMMITTED' below [mariadb] in /etc/mysql/mariadb.conf.d/50-server.cnf. 'transaction-isolation' was renamed 'transaction_isolation' as from MariaDB 11.x.

Philippe Liège wrote in RE: How to use MariaDB with Redmine 5.1.2:

'tx_isolation: "READ-COMMITTED"' in database.yml does the job when using MariaDB 10.11.6 (Debian Bookworm).
I also also had to insert 'transaction-isolation=READ-COMMITTED' below [mariadb] in /etc/mysql/mariadb.conf.d/50-server.cnf. 'transaction-isolation' was renamed 'transaction_isolation' as from MariaDB 11.x. No need to put READ-COMMITTED inside double quotes according to the MariaDB's help page.

Thank you for the suggestion, I hope my problem will also solved.