How to fix a PostgreSQL database connection error caused by exceeding the connection limit?

The error of exceeding the maximum number of connections in PostgreSQL occurs when an application or several running processes open too many simultaneous sessions to the database, exhausting the limit set in the server configuration file. This often happens in development environments where hot code reloading creates new connections without closing old ones.

To temporarily resolve the issue, you can connect to the DBMS with superuser privileges and forcefully terminate frozen active sessions using a special system query. After that, it is recommended to increase the max_connections parameter value in the database configuration file if your computer's resources are sufficient to handle the increased flow of simultaneous queries.

To prevent such situations in the future, it is strongly recommended to use connection pools. Tools like PgBouncer allow you to efficiently manage connections by reusing already open sessions instead of creating new ones for each individual request from your application. Also, make sure that your code always correctly closes connections after finishing work with the database.