Hi Paul, my guess is that the DB crashed so the 'tc.log' file was created and it prevent the mariadb-server to start again.
Let me check with the dev team were to investigate on this possible crash and I will come back to you. In the mean time, if you want to continue your investigation, I suggest you to take a look at: https://jira.mariadb.org/browse/MDEV-16442?jql=text%20~%20%22tc.log%22 Faustin
