You may be seeing this error message if you created a model with a newer version of SketchUp and you'd like to open the model with an older version of SketchUp. Note that every major version of SketchUp has a unique version of the *.skp file format, however recently with the 2024 release this has now gone versionless. This means that for 2021 and up you should not receive this error but simply a warning that an issue could occur.
If you need to open a 2024 model into 2018 for example, you may have to try different import options or even look to plug-ins that can change some settings. But if this scenario does come up please feel free to get in contact for more bespoke support.