You are working with postgres sql and get the previous message
You have reached the limit for database sessions which is 100 by default
You have reached the limit of database sessions. (default: 100) You need to increase the server's limit on how many concurrent backend processes it can start by changing the "max_connections" value in postgresql.conf and restarting the postgres server daemon.
Please do not "kill -9" the postmaster! This could damage your database. If it is unlikely that you reached this limit than you have to review your code and try to find out why the these processes are started all the time. In this case they might be idle.
About the Author
Wim Peeters is electronics engineer with an additional master in IT and over 30 years of experience including time spent in support, development, consulting, training and database administration. Wim has worked with SQL Server since version 6.5. He has developed in C/C++, Java and C# on Windows and Linux in different European countries and different European languages. He writes knowledge base articles to solve IT problems and publishes them on the Lubby Knowledge Platform where he is one of the most important contributors and the main developer.