Since some weeks I start to get this error opening a product detail view from the inventory -> product list view:

On the left the error from the application (same on the log) on the right the Chrome console error. the Http2 error are linked to a full connection pool error message on the log (I've increased the db_maxconn to 90, but the error is still there)

Checking on the server there are about 2GB of free Ram, and checking on the active connection the low is very low, about 2 user connected.