4.2 release security exception

I changed from 4.1.1. to 4.2.0 When I run my program, have no errors and I go to the webpage I get the following error: java.lang.SecurityException: File requested outside of webroot: '' would translate to 'C:\Mendix_Deployment\Development\Demo\421test\deployment\web\index.html'. I checked if I have this file, I cleaned my deployment directory, I have thrown away my current 4.2.0 modeler and reinstalled it. I started a new test project, I always get the same error message. I checked if I have the same problem with 4.2.1. and here I encounter the same problem. The modeler 4.1.1. still works fine. Has anybody encountered this problem before, and even better how to fix it?
1 answers

Do you perhaps have another webserver running that is listening to the default address http://localhost:8080? If so try setting your mendix app to a different port.