Why does the Network License Manager exit with message 'Warning: Maximum connections to the server has reached. Please disconnect some clients from the server"?

Why does the network license manager quit with the following or similar message:

ERROR: (lmgrd) Warning: Maximum connections to the server has reached. Please disconnect some clients from the server (MLM) Lost communications with lmgrd. Communications error. Connection closed. Exiting. (MLM) EXITING DUE TO SIGNAL 28 Exit reason 5

Answer 1

[MathWorks Support Team]

This has been a known issue in earlier versions of the network license manager. The error message being displayed seems like a failure with too many open file descriptors. While there are no guaranteed solutions, the best thing is to try the latest version of the license manager for MATLAB.

How do I update the Network License Manager?

https://www.mathworks.com/matlabcentral/answers/514971 

An alternative solution would be to set a LM_SERVER_HIGHEST_FD environment variable on the server machine and set it to 1023. The environment variable is used to set the highest file descriptor value, above which the license server will not access. 

This will not prevent the message from appearing in the log file, but it should help prevent the crash.