Did a crtitical update now getting errors
Most likely you've got an Assets field inside of a Matrix field somewhere on your site and you're referencing project-images/{slug} in that field's upload location setting when it should be project-images/{owner.slug}.

At some point, those settings were more loosely enforce, but now the error you're getting will be shown if it is incorrect.

See here for more info: https://craftcms.com/docs/assets-fields#dynamic-subfolder-paths