Message "all Micro Focus Cobol server licenses are in use"

In systems with w10 installed and Server for cobol 5.1 rev 18 license, for 10 concurrent users, when starting a Cobol application made with NE, this message appears, as if the user counter remains in memory or in processes running. It does not happen in systems with Win7. To solve it, it forces to have to restart the PC or to close session.

What is the cause of the error and how to solve it?