Mysql – How prepare and transfer database from thesql 5.7 to 8.0.19 since thesql_upgrade has been removed

The error log of MySQL records the details why MySQL can not restart, check the error log and update it in Questions would be helpful.

If MySQL is installed by apt-get or some other system's ways and uses the default configurations, error log always in /var/log/mysql.

If my.cnf changes, check the modified my.cnf in /etc/mysql/my.cnf or other paths to find the log_error param.

I suspect this may be caused by a bug that happens when in-line upgrades go from 5.5 to 5.6 to 5.7 then finally 8.0.

The suggestion to deal with this is to run optomize table on every single table while in version 5.7. Once the 8.0 upgrade is attmpted, it is too late because you cannot go back.

I am giving up, rebuilding this server from scratch, then install 5.7 and perform the optomize table then try the upgrade to 8.0 again.

Good thing I have another 5.7 server running and a full backup of all the data.