Hello Rosaliejam,
Thank you for reaching out in Apple Support Communities. We understand an error message appears, when you attempt to sign in with your Apple ID account for the Messages app on your Mac. In addition, the Photos app is not syncing to iCloud. We'll be happy to help.
To help troubleshoot the error message that appears for iMessage, we recommend to follow the steps outlined in this helpful article: If you can't sign in to your iMessage account or FaceTime on your Mac
In reference to the Photos app not syncing to iCloud, we recommend to verify that iCloud Photos is turned on. Please open the Photos app on your Mac and navigate to the menu bar by selecting, Photos > Preferences > select the "iCloud" tab > verify that, "iCloud Photos" has a check mark.
You'll also want to verify the recommended settings for your Wi-Fi routers and access points. This will help ensure a reliable Wi-Fi connection for best performance on your Mac. Here's an article with the proper steps: Recommended settings for Wi-Fi routers and access points
Please let u know if that helps.
Kind regards.
