I had the same error and got it working by:
- Removing my custom widgets
- Deleting the deployment and .mendix-cache folders and the launch file
- Restarting my PC
- Adding my custom widgets again
I am not sure what made the difference and i don’t think the custom widget part applies in your case, but in my case the above made my Studio Pro “run” working again.
Restarting the computer or close all Mendix activities in the task manager worked for me