MySQL server requested authentication method unknown to the client

I’m using docker-compose to run WordPress, MySQL and phpMyAdmin, but am pretty much a compose noobie. Now “docker-compose up” fails with the message "The server requested authentication method unknown to the client [caching_sha2_password].” I’ve seen postings saying that MySQL changed their hashing method. Presumably I need to either specify or select the new hashing method or downgrade MySQL. The question is, how do I fix it?. (My YML file specifies version 2.) Thanks