uploading library stuck

Good afternoon peterfromloudonville,

Welcome to the Apple Support Communities!

Congratulations on the purchase of your MacBook Pro! I understand you have iCloud Photos enabled with 30,000 photos and 1500 videos and you are trying to update this library on your MacBook Pro. My library has over 30,000 images and videos as well, so I know how important these memories are and I'll do my best to help you with this!

Peter, could you please provide little more information about your new computer?

• When you set up your MacBook Pro, did you restore your user account, settings and data from a Time Machine backup of a previous Mac?
• On your previous Mac, were your iCloud Photos optimized or did you have the originals downloaded to your hard drive?
• What operating system are you running on this Mac, and how much storage space do you have available?
• You confirmed the complete library is showing on your iPad and iPhone. Can you confirm everything looks correct at www.icloud.com as well?

Set up and use iCloud Photos

Photos User Guide - macOS Catalina

Quit the Photos app and restart your computer to refresh it and re-establish a connection to the internet.

Check to see what your internet connection download speed is. A wired connection is much faster than a Wi-Fi connection when you are working with such a large library.

Photos User Guide - Create additional photo libraries in Photos on Mac

Let's create a new test library in the Photos app to make sure there are no issues with the application.

• Press and hold the Option key on your keyboard, and click the Photos app. You will see the option to create a new library.
• Save it in the Pictures folder and call it "Test Library."
• Now we are going to put some "known good" photos in the new Test Library to confirm the application is working properly. We'll use the Desktop Pictures on your Mac to do this.

1. Open the Finder application.
2. Click Go > Go to Folder (or press Command, Shift, G)
3. Type /Library/Desktop Pictures
4. Click Go

• Select 5 images and drag them to the Photos icon on your Dock to import them into the current Test library.
• View, edit and organize these files as you normally would in the app.

Peter, please reply to this thread with an update regarding the information requested, and the results of the initial testing of the Photos app with a new library, and we'll continue troubleshooting from there.

To give you a roadmap, these would be the next steps:

If the Test Library works as expected, quit Photos.

1. Connect your computer to your modem/router using an ethernet cable to try with your current network, or take your computer to a different, faster network.
2. Then press and hold the Option key when clicking on the Photos app on the Dock and select the iCloud (System Library) again.
3. If the update process begins again, it could take several days for a library this large to update.
4. If the issue persists, you may need to repair the library - How to use the Photos library repair tool

If the Test Library does not work as expected, quit Photos and then create a new User Account and follow the steps above in the User Account.

How to test an issue in another user account on your Mac

Take care.