The mentioned solution actually provides good information but does not solve the problem. I had a similar issue with Matlab and only after Matlab updated their code did the problem get solved. Their update required re-basing onto a version of MySQL connector that was 'modern' for MySQL 8, and also to remove the code that used tx_read_only from an earlier MySQL pattern. I don't know where the parameter is being used in Mathematica so cannot eliminate that usage. Specifying read only is not appropriate, and neither is specifying read only = false or a default (no specification), since both generate that parameter to the java connector.
More investigation continues.
Thx
D
