I have just moved from Photoshop 2020 to Photoshop 2021. I didn't actually want to but 2020 just stopped working. When I try to open an image in 2021 all I get is a green screen. And the Tools Palette has no familiar tools just a few new ones I've never seen before.
I am not amused by this. I don't mind a few changes when there's an upgrade but I expect the program to continue working. Adobe, please explain what the hell you have done!
I am running mac OS Catalina on an iMac with 24Gb RAM.
When I try to open an image in 2021 all I get is a green screen.
Screen capture would be useful. So no matter what image you open, it only shows up green?
First, try disabling GPU in the preferences (Preformance tab). Any better? If turning OFF GPU works, it's a GPU bug and you need to contact the manufacturer or find out if there's an updated driver for it. Also see: https://helpx.adobe.com/photoshop/kb/acr-gpu-faq.html
Author “Color Management for Photographers" & "Photoshop CC Color Management" (pluralsight.com)