Hello angelageog,
Thank you for using Apple Support Communities.
I see that you are getting an unexpected error has occurred message when trying to order a project in Photos. I create and order books as well in the Photos app, so I know how important it is we get this issue resolved. I have something for you to try.
I advise to check your Internet connection, then make sure that you're using the latest version of Photos and that your Apple ID billing information is up to date. Also, use If you can‘t order prints or projects, from Apple using iPhoto, specifically, this section:
When you try to place an order, you might see a message that reads "An unexpected error has occurred. Please try again later."
To fix this issue, update your information in the Apple Online Store:
- Go to your Apple Store Account.
- Under Account Settings, click "Update your Apple ID email address and password."
- If asked, sign in with your Apple ID and password.
- Next to Payment Information, click Edit.
- Re-enter all of your information as it appears on your credit card statement, then click Save.
Have a great day!