Cannot move iPhone photos to Photo Library on my external hard drive

I am having this same issue exactly the way it is being described. My external HDD is formatted correctly and I tried to copy the whole photo backup from my external HDD back to my MacBook. The import worked on that. I then copied it back to the external HDD and it doesn't allow to import. It used to work fine before the 17.4.1 update. I also updated my MacBook and iPhone to the latest version but no luck. Is this another new way for Apple to annoy its users?

Guys, encountered similar issue that's why I searched in threads like these to solve the problem. Well, I found the solution! It seems to be a bug in iOS 17 and iOS 17.5.1 upgrade and a quick restart for both units solved the problem. No, Apple's silence didn't help. Good luck to us!

The first question we have to ask is, how is your external drive formatted. This is because, to avoid damaging the Photos Library an external drive must be formatted in either APFS format or Mac OS Extended (Journaled) format. Additionally, the drive can not have had Time Machine on it since it was formatted. The newest macOSs won't even allow a Library on a non-Mac formatted drive to open. See this:

Move your Photos library to save space on your Mac - Apple Support

We need to know that answer to that before we can go much further...