I have also had this error, for context I was making a weapon for a character and had dozens of different versions all lined up, and we had decided which one to go with so deleted the rest and clearing out their components, so now there was just the one left, then saved and got the error message, I would have thought it would have run out of space when there where dozens of them not when there is only one, it doesn’t make any sense to me as I run out of data when I freed up data.
could the error message itself be an error? because my files are still saving fine
(after the error message pops up open a new tab of sketchup and look in your files you should see the latest version there and you can access it just fine)
sorry for the long ramble but I hope the save…thing works for you as well and you can get back to normal whilst the people at sketchup can figure out what is happening.