How long does updating docker_manager take?

How long does it take to do a docker manager upgrade? Should I backup anything first? Does it disrupt the forum during update so that I should do it during the night, for example?

Five or ten minutes, depends on your machine and how much RAM you have.

Yes, you should always backup before an upgrade action - preferable also download the backup just in case.

No, it doesn’t disrupt the forum if you update using the web interface. But, it’s possible attempting to update will expose that you need to do a command line update. In this case, I think the forum might already be stopped. Perhaps someone can confirm.