On Mon, Dec 07, 2020 at 04:27:46AM +0000, Monit wrote:

Connection failed Service rdsys-backend

Date:        Mon, 07 Dec 2020 05:27:46
Action:      alert
Host:        server01
Description: failed protocol test [HTTP] at [bridges.torproject.org]:443/status [TCP/IP TLS] -- HTTP error: Server returned status 400

FYI, this was a hiccup after adding rdsys's backend to monit. The check now works and the service is running.