Error:

Auto-attach to process '[4572] aspnet_wp.exe' on machine 'PRABAKAR' failed. Error code 0x8013134b.
OR
Error While Trying to Run Project : Unable to start debugging on the server.

Cause:
there are many reason for this error.the one possiable reason is when u r migrating form one version to another versionwe will get this type of error.

Solution :

select the project in the IIS and go to the properties and select the ASP.NET Tab and change the version,possiable to the previous version.