#jitsi occasionally pops up Certificate Error dialogs for chatme\.im ... though their Web site uses #LetsEncrypt, the #XMPP server uses Commodo #PositiveSSL, which the client doesn't always trust. I haven't been comparing the hashes to see whether the "don't trust" is due to a false cert. I just cancel and close the client, then wait a few minutes and reopen Jitsi. ( I would prefer #LEcrypt to Commodo. )