Your first suggestion is correct. This is not a bug, but rather a problem with the HDMI cable itself. I turned “automatic suspend” back on and removed “MUTTER_DEBUG_FORCE_KMS_MODE=simple” from the environment so that everything was back to normal. I unplugged the HDMI cable from the TV and laptop, then plugged it back in. I switched it to external-only mode and waited 15 minutes for the laptop to suspend, then unplugged the HDMI from the laptop in that external mode. As a result, my laptop screen turned back on, unlike before when it went black.
I initially suspected this was a bug, but it wasn't. So perhaps the solution to this problem is to replace the cable. Sorry for the misunderstanding. I am also very grateful for all the responses and suggestions provided. This is all I can report so far. Thank you very much. -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to mutter in Ubuntu. https://bugs.launchpad.net/bugs/2138173 Title: blank screen when external monitor is not connected To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/mutter/+bug/2138173/+subscriptions -- desktop-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
