If your error looks like this https://gyazo.com/4bb0edc845c1688fbe8c1561dfb1d1f0
I have found a temporary fix until the FiveM team manage to fix the issue.
Step 1: Run the FiveM app like normal and wait for the error to show and don’t close the error message!
Step 2: Run the FiveM app again while the error message is open and from my experience it will launch the game. The loading times will be a tiny bit longer so just be patient.
I’m glad I could help