I'm getting an invalid filename message (PC)

Situation: every few minutes, an "invalid filename" message is displayed.

SketchUp automatically saves your files while you are working on them, by default, every five minutes. This message is displayed when SketchUp is unable to write the auto-save file to the default location.

On a PC, the auto-save file is saved in the same folder as the model is saved. If you haven't yet saved your file, by default, it is saved in your "My Documents" folder; however, it's possible to change the default location where models are saved by changing a setting in the SketchUp Preferences. This issue happens if you don't have full write permissions to that location.

To check this:

1. Open the "Windows" menu.
2. Click "Preferences."
3. In the left pane, click "Files."
4. In the right pane, copy the path for models.
5. Open Windows Explorer, paste the path into the address bar, and press Enter.
6. If an error message is displayed, you don't have the necessary write permissions for the default location where models are saved. You can either change the permissions to the default location or change that location in the SketchUp Preferences dialog box. To change the location, just click the folder button next to the path for models, and then select a different location.