We hit this when loading a bunch of records in data loader where many of the records were child records to a single parent. Is your page trying to save several child records of a single parent at once?
We just came across this problem in the PageBuilder (we are running Skuid 7.36.1).
No one of us is editing the same page and neither of us is able to save their page. It's the first time that this happened and we didn't modify anything in the backend (according to this post this error can be thrown when some things are changed/revalidated in the backend).
EDIT: As stated in the post mentioned above, the problem resolved itself (magically) after 10-15 minutes.