When starting a second instance of ArcMap on the same computer the following error may occur:
"No PLTS licenses are available"
Communication between the license server and ArcGIS has been interrupted or blocked.
Solution or Workaround
Switching the license manager to a static port and then ensuring that these ports are open may alleviate the communication problem.
- Follow the steps in the article linked in the Related Information section to set the ArcGIS license manager to a static port.