SAP Note 13757 - RFC error: no free connection available

Symptom:

Error ID: CALL_FUNCTION_*
Remote function call terminates with the message

"No free connection available".

Cause and prerequisites

One of the administration tables in the SAP System overflowed

Solution
The administration tables for open connections can be set using
the following parmeters:

The max. number of all active connections via one SAP gateway is
set using profile parameter

gw/max_conn

The default value is 20. It can be set to 100 (or more) without
causing any problems.

An additional restriction exists for the maximum number of open
connections for one application server. This is controlled by the
parameter

rdisp/max_comm_entries

The default value is 100. You only need to increase this value when you have increased the parameter gw/max_conn.

Please note: changes to profile parameters only become effective after the instance has been restarted.

Key word: ABAP/4