Does turning off »Use Graphics Processor« in the Performance Preferences (Photoshop > Preferences > Performance > Graphic Processor Settings) and restarting Photoshop have any bearing on the issue?
What have you done for trouble-shooting so far?
Restoring Preferences after making sure all customized presets like Actions, Patterns, Brushes etc. have been saved might be a good starting point:
That did not solve the issue. I did also try restoring preferences, I have increased RAM usage to allow for 80%, I have uninstalled and reinstalled Photoshop, restarted my computer, tried opening files stored on an external drive as well as my computers internal drive. Nothing seems to help.
In addition to Disk Utility showing an ok drive, I also checked my drive with DriveDX and it shows a health of 100%.
SOLVED! I just got off the phone with Adobe tech support and after trying many things that did not work, we created a new user account and opened Photoshop with that account. It worked! ACR opened right up. Apparently it was something with my current user account. Later today I will be reformatting my hard drive and starting with a fresh installation.
I hope this solution works for anyone else having this issue.
Update: I used Adobe Creative Cloud Cleaner Tool and uninstalled Photoshop. Then I wen't in to my /Library/Application Support/Adobe? and deleted the Photoshop and Camera Raw folders. Then I reinstalled Photoshop CC and everything works perfectly. No need to start with a fresh OS installation.
Downloading & running the Adobe Cleaner Tool after you uninstall all apps from your computer could help too...
Then reboot your computer (don't skip this step), and proceed with reinstalling the tools you want.