I have 1.26 gig photos on iPhoto not seem to be synced with iCloud. and Error message when I try to sync iMac to iCloud

LGH in FL wrote:

iPhoto is deprecated since 2015...

When you Launch Photos.app hold the Option key down and select your default photo library if necessary.

Otherwise simply launch Photos.app.

ref: Designate a System Photo Library in Photos - Apple Support

Where is you library located? If on an external drive how is the drive formatted? If must be formatted as shown if to be used to house and use a Photos library and use iCloud Library:

Yes, that's the iPhoto application which is not compatible with the Ventura system as the "forbidden" sign over it indicates. That's an app, not the library which contains photos.

If you hold down the Control key and launch the Photos app you'll see any potential libraries on your drive(s). Photos libraries will have this icon:

and an iPhoto library will have this icon:

The image you posted is for the application and it does not contain any photos.

LGH in FL wrote:

As far as I can tell it’s an iPhoto folder on my iMac and the error message comes up on that and on photos when I try to sync across my devices. This answer doesn’t help me because I don’t understand what to do to fix the problem.

Is the iPhoto Library stored on an external drive? If so, the external drive needs to be either Mac OS Extended or APFS. You would need to move the Library to a drive that is formatted correctly. You cannot format the drive it is on until you move the Library as formatting will erase the drive.

Post a screenshot of what you're referring to, i.e. the folder or library.

LGH in FL wrote:

I have 1.26 gig photos on iPhoto not seem to be synced with iCloud. When I try to sync my iMac photos to iCloud, I get a message: " iCloud Photos is only available on macOS Standard, MacOS Extended and APFS formatted volumes. how to fix?

ref:

About iCloud Photos and My Photo Stream - Apple Support

https://support.apple.com/guide/icloud/set-up-icloud-photos-mm7e90c1ba48/icloud