Every database is having some number of connection limits which you can increase up to an extend.
But database can support up to an number of connections.
This error occurs when we open a connection and forget to close that. Verify each line of your code and make sure you had closed the connection after completing your database operations.
I had faced this error in C# My sql application. I had crossed verify my code and find a code where I am not closing my connection after completing my operations. I had simply write connection.Close(); and it had worked.