I skipped upgrading the iMac server’s OS to macOS 10.15 Catalina last year mainly due to the removal of 32-bit application support. After a year, the clean-up of obsolete apps was complete, paving the way for the upgrade.
During the preparation, there was a bit of a hiccup with the MySQL database, But putting the data to a new one largely solved the issue and the website ended up loading much quicker. Two minor errors occurred after moving to the new database, which were quickly resolved by editing the configuration file:
1. "Query failed: Out of sort memory, consider increasing server sort buffer size"
Solution: increase sort_buffer_size from the default of 262144
2. "Query failed: Expression #1 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'blog.multilingual_body.value' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by"
Solution: remove only_full_group_by in sql_mode
sql_mode=STRICT_TRANS_TABLES, NO_ZERO_IN_DATE, NO_ZERO_DATE, ERROR_FOR_DIVISION_BY_ZERO, NO_ENGINE_SUBSTITUTION
With all the pieces ready I went with the installation of macOS 11.0 Big Sur. It took about an hour and except for a prolonged setup time of the iCloud, things went smoothly.