Confluence failed to start after updating MySQL database to version 8.0.29 or above due to unsupported database collation utf8mb3 error.

Issue Summary

Confluence failed to start after updating MySQL database to version 8.0.29 or above (tested with upgrade to MySQL 8.0.30) due to unsupported database collation error.

Steps to Reproduce

1. Create a Confluence database in MySQL 8.0.28 or older with utf8 character set and utf8_bin collation.
2. Install Confluence 7.13.x and connect to the MySQL database.
3. Shutdown Confluence.
4. Upgrade MySQL to 8.0.29 or later.
   Tested with upgrade to MySQL 8.0.30
5. Start Confluence.

Expected Results

Confluence Should start correctly. The Health Check should pass in case MySQL version is 8.0.29 which has the utf8m3 as the new display name for uft8 collation:

The server now uses utf8mb3 in place of the alias utf8 for character set names when populating data dictionary tables from built-in character sets. This affects the display of character set and related information in the MySQL Information Schema tables listed here:

More information can be found on MySQL 8.0.29

Actual Results

Confluence failed to start due to database collation error:

Workaround

As mentioned in Database Setup For MySQL documentation, "If you have Confluence 7.3 or later, you can change the character set and collation to utf8mb4 and utf8mb4_bin to avoid this issue". The following knowledge base article explains the steps:

• How to Fix the Collation and Character Set of a MySQL Database manually