Achyut Tripathi makes a connection:
Database connections are essential for any program to manage and access data in the database. When a server already has too many active and open connections – a result of a large number of users creating numerous, simultaneous demands on the system – no new connections can open, and the system indicates that it has reached its maximum connection limit.
This issue can be caused by several factors, including connections that are opened unnecessarily and no longer used by the application, programs that create a large number of connections, incorrectly configured connection pools, and a sudden increase in traffic.
When these issues aren’t managed properly, the system encounters request failures – resulting in no new connections being made.
Read on to see how Postgres handles these and what you can do if you find yourself in that situation.