The file was saved in 2.0.17457 and you are on 2.0.16976 . Now the real error is that we are not showing the right message which should read something like : Forward compatibility is not supported: 2.0.16976 - The file you are trying to open was last saved in a newer version of the software. It cannot be opened!
The reason we suspect that you are not seeing the new update available to you is the short cut. Can you please do the below for us?
1. Manually Open latest fusion
1. Close Fusion
2. Delete the Fusion 360 short cut you have
3. Go to C:\Users\USER ID\AppData\Local\Autodesk\webdeploy\production\a folder that shorts with 6a0c961*\Look for the FusionLauncher.exe (like \AppData\Local\Autodesk\webdeploy\production\6a0c9611291d45bb9226980209917c3d\FusionLauncher.exe)
4. Run Fusion from here
Now 2 things should happen:
1. When you open the same file it should tell you the right message that this was saved in a newer version AND also you should start seeing a new version being downloaded.
Similar solution is provided here
https://forums.autodesk.com/t5/fusion-360-support/unable-to-open-because-of-sync/m-p/11845579#M...
2. Also you can use Fusion Service Utility to repair fusion installation for you.
https://www.autodesk.com/support/technical/article/caas/sfdcarticles/sfdcarticles/How-to-launch-the-...
Please let us know what you see.
Ideally you will need to be on the newer version and this file will open.
