SketchUp Pro Not Saving

I am using Sketchup Pro 2022, and have been for the last half of a year. Today for the first time, when I went to re-save my file that I’ve been working on for a while it didn’t save and had a pop up that said “SketchUp is unable to save your model. It is recommended that you attempt to save your model to SketchUp version 2020 or earlier to prevent any loss of data.” It’s never done this before and I don’t have the 2020 or earlier version, I bought and have always been using the 2022 version. Please help me save all my work I’ve been doing.

Where are you trying to save it to?

That message can happen if some geometry was created that confuses the 2022 validity checking. If you did save it as a 2020 file it would reopen in 2022, but is likely to still have the same geometry causing a problem.

The number of oddities that SketchUp can cope with has increased over time. You could make sure you’re on the latest 2022, and as you have a subscription you could also try 2023. No need to uninstall 2022, but do sign out from your account in 2022 before signing in with 2023.

Here is the 2022 installer:

and here’s 2023:

You can save your model as a 2020 skp file from your 2022 version, and you can also open a 2020 skp file with sketchup 2022, you don’t need to get the 2020 version to do that.
Try to do what Colin suggested, maybe the sketchup 2023 can handle better your file, you don’t need to pay more to update, the subscription allows you to get the latest version when it’s released.