mysql 5.7.39 failed to start after adding character_set_server=utf8mb4 in my.cnf file

[Navas]

i am trying to set up jira server on ubuntu 18 server for my learning/testing purpose.

following the link Connecting Jira applications to MySQL 5.7 | Administering Jira applications Data Center and Server 9.3 | Atlassian Documentation before proceeding to install jira server. i have tried to modify my.cnf file with "character_set_server=utf8mb4 in my.cnf" , which causes mysql service fail to restart. Please help here as i cant continue further.

[Nic Brough -Adaptavist-]

Welcome to the Atlassian Community!

What errors are you getting in the MySQL log or startup call?  Are you sure its the character set that is going wrong, or could it be something else?  Is that setting in the right section of the file?