Try clearing the deployment directory by selecting Project → Clean deployment directory. Then try to start again.
If that does not help, go to the project's directory in Explorer and remove everything from /deployment. Then try to start again.
Have a look at the following forum posts:
https://forum.mendix.com/link/questions/91660
https://forum.mendix.com/link/questions/96069
These might contain the solution for your case as well.