mod_chat breaks moodle installation on MySQL 8.0.3

Note: It's much more convenient to run MySQL 8 via docker: docker run -p 3306:3306 -e MYSQL_ROOT_PASSWORD=moodle -d mysql:8 --character-set-server=utf8mb4 --collation-server=utf8mb4_bin --innodb_file_per_table=On Test 1 Install a new site running at least MySQL 8.0.3 - 8.0.5 will be fine too unless new issues will be introduced by this new version, which should be fixed but in a new separate issue -  on integration. Confirm you can install with no errors. Create a course. Add a chat. Write a few messages. Confirm there is no error. Backup the course: confirm the 'system' is still there as part of the description of the 'message' payload. Restore it as a new course. Confirm the 'system' field values in the backup persist as 'issystem' in the DB. Test 2 Install a new site running MySQL 5.x or Postgres on Stable. Upgrade to Integration. Check the tables 'chat_messages' and 'chat_messages_current' have the column 'issystem' and not 'system'. Test 3 Create a site in 3.2, running on another DB instance since MySQL 8 support comes with 3.3.4+ and 3.4.1+ (-- MDL-59100 - , --- MDL-59099 --) Create a course. Add a chat. Write a few messages. Backup the course. Restore it as a new course on your testing site above (in Test 1). Confirm the 'issystem' field into the DB reflects the 'system' values from the backup. Same tests should be performed using: chat as daemon Moodle Mobile as client