When testing in a development environment, and the site has an https binding in IIS, the popup error shows that; the process cannot access the file because it is being used by another process.
- Log on the computer that is running IIS by using an account that has administrative permissions.
- Click Start, click Run, type cmd, and then click OK.
- At the command prompt, type the following command:
- Search for that process ID in the task manager with view->select columns-> process id checked
- Terminate that process
- Restart the IIS
Note: if you have Skype™ installed try exiting that one first
For more information also take a look at this article, https://support.microsoft.com/en-nz/help/890015/you-receive-a-the-process-cannot-access-the-file-because-it-is-being-u