Unable to save photos on my MacBook Pro after editing them

Give this a try: boot into Safe Mode according to How to use safe mode on your Mac and test to see if the problem persists. Reboot normally and test again.

NOTE 1: Safe Mode boot can take up to 3 - 5 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

NOTE 2: if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode. This makes it act as a wired keyboard as will insure a successful boot into Safe Mode.

Are you increasing the size or reducing it. If reducing you can use Photos to export it to a different, smaller size. Import it into a Photos library and then export out as an edited image and set the Size to Custom. Then make your choices. See if that will work.

Also have you installed and run any "cleaning", "optimizing", "speed-up", anti-virus or VPN apps on your Mac?

Where ist this local folder "Photos" located? In your own user home folder or outside your user folder, for example in /Users/Shared ?

It is difficult to work with items in /Users/Shared. Try to save your edited version to a folder in your Pictures folder or any other folder in your user home folder. Does that work?

AZsport115 wrote:

No cleaning, optimizing, speed-up, anti-virus, or VPNs.

The Automator quick action was created because we do this so frequently that using the Photos app is prohibitive.

The Automator quick action creates a folder called Photos.

It then copies a photo from a different folder into the Photos folder.

After doing so, it reduces the file size of the photo it just copied.

However the now resized, smaller photo is not editable. Moving the photo to the desktop does not allow it to become editable, which tells me the folder permissions are not a problem. Somehow the quick action from Automator appears to be making the photo not editable. I can't understand how macOS can tell me I don't have permission to edit a photo when the current user is admin, the photo itself, its enclosing folder Photos, and any parent folder all have Read & Write permissions for all users. I'm at a loss as to where I would go and what I would do to further expand permissions for this image file. Permissions seem to be maximum--any user can Read & Write any photo and any folder.

Are you resizing the image file's size rather than the image dimensions?

I use an Automator app to scale my screenshots by 72% so that are a reasonable size to add to post in these forums. It's because the iMac's screen was a 5K Retina screen and had too many pixels to add to posts.

But I do it outside of the Photos library and the Pictures folder. I do it on the Desktop. This is what the app in automator looks like:

I've not has a problem with the app in Big Sur, Monterey, Ventura and Sequoia.

I save the item as an application and drop the screenshots on it to convert. With that action in Automator you can also set the max width or max height in pixels .

Have you tried File>Export? I'm thinking that will bypass permissions.

I have copied photos to a local folder called Photos.

Copied from where?