Upgrading a QVSource or QVWebConnector component leads to the following error when starting:
System.Net.HttpListenerException (0x80004005): Failed to listen on prefix XXXX because it conflicts with an existing registration on the machine
The startup log reads:
Failed to listen on prefix 'http://XXXXXXX:YYYY/' because it conflicts with an existing registration on the machine.
In cases like those, QVSource or a third party application are already reserving the required endpoint (port).
A typical specific entry might read:
System.Net.HttpListenerException (0x80004005): Failed to listen on prefix 'https://+:5555/' because it conflicts with an existing registration on the machine.
An example scenario would be running QVSource with remote access enabled and then attempting to move QVSource to use SSL.
Resolution
Launch a PowerShell Command prompt as administrator and run:
netsh http show urlacl | where {$_ -match ':5555'}
Note we have entered the port number (which would have been the YYYY value in the above error message).
The PowerShell output will look like:
This indicates that an application (which might be QVSource) has already reserved this endpoint.
You can also enter netsh http show urlacl which will list all reservations on the machine with additional information about each but you will have to manually find the ones matching the port number you are using.
If this is the case, or you know that you are safe to remove this reservation, you can simply run the following command to delete the URL reservation:
netsh http delete urlacl url=http://+:5555/
NOTE: The value after url= must exactly match that shown from the result(s) of running netsh http show urlacl above.
Which should confirm the deletion:
QVSource will now start.
