Receiver shows the "A second transmitter attempted to connect. Please close it." message repeatedly

Issue:

The text "A second transmitter attempted to connect.  Please close it." message repeats continuously in the receiver window.

Solution:

The transmitter.html file is open in more than one application.  This issue is often caused by opening the transmitter file in a web browser for troubleshooting purposes without closing the transmitter dock in OBS first.  Close all open instances of the transmitter, including OBS docks, close and relaunch the receiver, then re-open the transmitter.html in the desired application.