Please try the following steps exactly as described, this should get you up and running.
For Windows:
1) Close all instances of SketchUp and LayOut. To make sure they do not continue running in the background, please go to your Taskbar and right click on any SketchUp or LayOut icons and select Close Window.
2) In Windows File Explorer, go to Windows (C:) > Users > your user name > AppData > Roaming > SketchUp [year] (C:\Users\username\AppData\Roaming\SketchUp\SketchUp[year])
Note: If you can't find the AppData folder, please open with Windows key + R (on your keyboard) and type %appdata%
3) Locate and delete the "login_session.dat" file
4) Restart SketchUp and login
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For Mac:
1) Close all instances of SketchUp and LayOut. To make sure they do not continue running in the background, please go to your Taskbar and right click on any SketchUp or LayOut icons and select Close Window.
2) Go to Finder, then click on 'Go' on the menu bar, then hold the 'Option' key.
3) 'Library' should appear in the list. Click 'Library'.
4) Navigate to Application Support > SketchUp (year) e.g. SketchUp 2026
Note: You can also do the same using 'Apple+G' and paste in: ~/Library/Application Support/, then navigate to your current SketchUp folder e.g. SketchUp( year)
5) Locate and delete the "login_session.dat" file
6) Restart SketchUp and login