Hi. I have a new MacBook pro and i can't open the Photos library. please help

What do you mean by „the library is on iCloud“? Is the photo library package stored on iCloud Drive or has the Photos lLibrary been syncing with iCloud Photos Library? Photos cannot work with a library stored on iCloud Drive. The syncing would damage the library package. But if you library has been syncing with iCloud Photos and all your photos and videos are still in your iCloud Photos Library, you can rebuild your library by downloading the photos to a new empty library.

• quit Photos, if it is running. Launch it again while holding down the options key. When the dialog to select a library appears select to create a new library, preferably in you Pictures folder.
• go to the Photos Preferences General tab and click „use as system photos library“.
• open the iCloud tab and enable iCloud Photos and Optimise Mac Storage, if you do not have much free storage.
• Wait for the photos to reappear in your library

Hi

Where is the library stored? If it is on an external drive, what is the format of the drive. And is the drive also used for time machine (or has it been in the past?).

If it is on your system drive, how did you transfer it from the old computer?

Do you have all the photos already in iCloud? If so, we could sync iCloud to a new empty library and solve the issue that way. Question above is still important though.

Could it possibly have come from a computer with a newer version of the Operating System? If your old computer had Monterey, and your new computer still has Big Sur, this is exactly what I would expect.

What happens when you try?

Try holding down the option key while starting photos. That should list all the libraries on your mac - select each in turn until you find the correct one.

That‘s great. You‘re welcome 😊