External monitor
I hooked up my MacBook Pro to an external acer monitor via HDMI cable and was messing around with the refresh rate. now my acer monitor says “Input Not Supported”.
Question marked as
It it was working before, what you've likely done is to set a parameter the monitor cannot support. Just because a selection is available does not mean it will work with all monitors.
Open the lid and start resetting parameters. If you have a Reset to default selection do that first. If not, begin at the lowest resolution/refresh rate available and retry until you find one that works.
You can research the Mac and the monitor to get the specs, but sometimes simple trial and error is quicker. When you hit one that works, you'll know it.