That option is used by default in disco's /etc/mysql/mysql.conf.d/mysqld.cnf file, and removed on a release upgrade to mysql 8. I just did such a test. But you have it in /etc/mysql/my.cnf, I wonder if the upgrade procedure looks at that file.
In any case, I suggest to remove this option from your configuration and then try to finish the upgrade:
Thanks for filing this bug in Ubuntu.
I see the following messages in the mysql log file:
2019-11- 01T08:12: 31.317917Z 0 [Warning] [MY-011068] [Server] The syntax 'expire-logs-days' is deprecated and will be removed in a future release. Please use binlog_ expire_ logs_seconds instead. 01T08:12: 31.319323Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.17-0ubuntu2) starting as process 11983 01T08:12: 32.177301Z 0 [Warning] [MY-010068] [Server] CA certificate ca.pem is self signed. 01T08:12: 32.179958Z 0 [ERROR] [MY-000067] [Server] unknown variable 'query_ cache_limit= 1M'. 01T08:12: 32.180190Z 0 [ERROR] [MY-010119] [Server] Aborting 01T08:12: 33.958062Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.17-0ubuntu2) (Ubuntu).
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From https:/ /dev.mysql. com/doc/ refman/ 8.0/en/ added-deprecate d-removed. html, we can see that the config option query_cache_limit was removed in 8.0.3:
"""
query_cache_limit: Do not cache results that are bigger than this. Removed in MySQL 8.0.3.
"""
That option is used by default in disco's /etc/mysql/ mysql.conf. d/mysqld. cnf file, and removed on a release upgrade to mysql 8. I just did such a test. But you have it in /etc/mysql/my.cnf, I wonder if the upgrade procedure looks at that file.
In any case, I suggest to remove this option from your configuration and then try to finish the upgrade:
sudo apt update
sudo apt -f install