@Mastodon update from 4.1.9 to 4.2.0 didn't work.
I'm using the docker version.. cd /mastodon/mastodon; docker-compose down; git fetch; git checkout v4.2.0; docker-compose pull; docker-compose up -d. Images were pulled succesfully and containers showed status healthy, but the website wasn't loading. Waited a few more minutes and finally reverted back to 4.1.9, which works fine.