Hi!
I don't believe this is something we've encountered before. Maybe removing the 3.4.02 update and downloading it again will help.
You can find the update file in:
Windows: %UserProfile%\Spine\updates
Mac: <user home folder>/Library/Application Support/Spine/updates
Linux: <user home folder>/.spine/updates
Just remove the file named 3.4.02 and start Spine, it will then download 3.4.02 again.
I hope this helps!