I have my Photos library on a separate HD. That HD is formatted in MacExtended and Journaled. It is an HD that is used for a Time Machine backup, but that backup is on a separate partition. I've never had an issue until this point.
MacBook Pro (2017 – 2020)
It sounds like you're doing what you need to do with your external hard drive. But have you checked the "Ignore Ownership" option at the bottom of the Finder info window for your drive?
Are you using iCloud to synchronize Photos on your devices? Do you have "Optimize Storage" checked? Can you open a Library on your on-board drive?
What have you done differently, recently, that preceded this problem? Did you update your operating system, or something like that? As a start, have you done these things?
* Restart the computer (of course)
* Use another library if you have one, or make a small test Library with a few pictures in it and see if the same thing happens.
* Make a new user and see if the same problem recurs with it
*Start in Safe Mode. This bypasses certain potentially disruptive processes. This is different for different computers, so see the link:
Start up your Mac in safe mode - Apple Support
One of these steps may fix the problem, but their failure to work is also diagnostic.
It sounds like you're doing what you need to do with your external hard drive. But have you checked the "Ignore Ownership" option at the bottom of the Finder info window for your drive?
Are you using iCloud to synchronize Photos on your devices? Do you have "Optimize Storage" checked? Can you open a Library on your on-board drive?
What have you done differently, recently, that preceded this problem? Did you update your operating system, or something like that? As a start, have you done these things?
* Restart the computer (of course)
* Use another library if you have one, or make a small test Library with a few pictures in it and see if the same thing happens.
* Make a new user and see if the same problem recurs with it
*Start in Safe Mode. This bypasses certain potentially disruptive processes. This is different for different computers, so see the link:
Start up your Mac in safe mode - Apple Support
One of these steps may fix the problem, but their failure to work is also diagnostic.
You did not mention if the external drive has a wired connection or is accessed over the network. Photos has not been designed to access a Photos Library remotely, if you are accessing the library over the local network, try to connect the drive with the Photos Library to a USB port on your Mac.
Ownership was okay. It was accessed via USB. The key was to log into another account. Thankfully, I had two of them set up. Once I did that, I was able to access via either account.
Cannot access my Photos Library.
