Photos library will not open (4302)

Running an iPhoto library from a NAS drive was never sanctioned by Apple. It did work for many until the more stringent protection features of Catalina came along.

You will have to copy the library to an EHD formatted as shown in this screenshot

connected directly by cable to your Mac and run it from there. This user tip explains it more fully: Where is it safe to store a Photos Library - 2019 Version

Hey there Nathan Gogol,

Thanks for reaching out to Apple Support Communities. I understand you’re having issues opening a Photos library. I’ll be happy to help with this.

It sounds like you’ve done some good troubleshooting so far. I know you mentioned you’re on macOS Catalina but please make sure you have the most recent version installed:

How to update the software on your Mac

If it still won’t open, ensure you have a backup or copy of the library saved to another drive before moving forward. Once you’ve done that, go through the steps in this link to check the permissions Photos library but do not go through the steps under ‘If the issue persists’:

Resolve issues caused by changing the permissions of items in your home folder

Boot into safe mode after that if you still have issues:

How to use safe mode on your Mac

While in safe mode, press and hold the Options key while opening Photos and select the library you’re having issues with. Then press and hold the Command and Option keys while clicking Choose Library. This will attempt to repair the library while in safe mode. See if the issue is resolved then.

Regards.

Being on the NAS probably has corrupted the complex ecosystem of permissions and hard links within the library. How many times have you tried to repair it?