This morning, I tried to upgrade MySQL 8:

mysql80-server upgraded: 8.0.22_1 -> 8.0.23

But then after upgrading. MySQL didn't start anymore !
It was broken:

2021-02-22T06:20:33.856568Z 4 [System] [MY-013381] [Server] Server upgrade from '80022' to '80023' started.
2021-02-22T06:20:34.351272Z 4 [ERROR] [MY-013178] [Server] Execution of server-side SQL statement '-- Create slow_log CREATE TABLE IF NOT EXISTS slow_log (start_time TIMESTAMP(6) NOT NULL DEFAULT CURRENT_TIMESTAMP(6) ON UPDATE CURRENT_TIMESTAMP(6), user_host MEDIUMTEXT NOT NULL, query_time TIME(6) NOT NULL, lock_time TIME(6) NOT NULL, rows_sent INTEGER NOT NULL, rows_examined INTEGER NOT NULL, db VARCHAR(512) NOT NULL, last_insert_id INTEGER NOT NULL, insert_id INTEGER NOT NULL, server_id INTEGER UNSIGNED NOT NULL, sql_text MEDIUMBLOB NOT NULL, thread_id BIGINT UNSIGNED NOT NULL) engine=CSV CHARACTER SET utf8 comment="Slow log"; ' failed with error code = 13, error message = 'Can't get stat of './mysql/slow_log.CSV' (OS errno 2 - No such file or directory)'.
2021-02-22T06:20:34.354494Z 0 [ERROR] [MY-013380] [Server] Failed to upgrade server.
2021-02-22T06:20:34.354946Z 0 [ERROR] [MY-010119] [Server] Aborting

Googling didn't solve my issue directly. So I tried to create this missing CSV file. (in the mysql database directory)
After this error I also received a missing slog_log.CSV.
Did the same thing.

touch ./mysql/general_log.CSV
chown mysql:mysql  ./mysql/general_log.CSV
touch ./mysql/slow_log.CSV
chown mysql:mysql  ./mysql/slow_log.CSV

Then it works again!

This seems to happen if you skip a certain upgrade. (from now on these CSV files are required). And these CSV files are only created in that particular update.. (not very robust!)