2452030 - Not able to login to Java/Portal ""AN EXCEPTION OCCURRED WHILE PROCESSING YOUR REQUEST"

• Not able to login to Java /Enterprise Portal. Cannot see login page. You get an error message ""AN EXCEPTION OCCURRED WHILE PROCESSING YOUR REQUEST".
• Java server is up and running.
• In default traces (/usr/sap/<SID>/<instance>/j2ee/cluster/serverx/log) you see this error

             An exception was thrown in the UME/ABAP user management connector that was caused by unavailability of the RFC communication with the backend system: "com.sap.conn.jco.JCoException: (102) JCO_ERROR_COMMUNICATION: Connect to SAP gateway failed
            Connection parameters: TYPE=A DEST=UMEBackendConnection ASHOST=<hostname> SYSNR=<sysnr> PCS=1
            LOCATION SAP-Gateway on host <hostname> / sapgw00
            ERROR max no of cpic clients exceeded (<nnn>)

• This only happens when the number of users exceed the <nnn> mentioned in the above error message. For example if the message says "ERROR       max no of cpic clients exceeded (300)", then the issue occurs only if the users exceed 300.

  SAP Netweaver Application Server Java

UMEBackendConnection,JCO_ERROR_COMMUNICATION,ASHOST,UME,ABAP,cpic,sapgw00,gw/max_sys,"exitcode -11113",ume.r3.connection.master.gwhost,ume.r3.connection.master.gwserv,netweaver,j2ee,java, /nSMGW, portal,RFC_ERROR_COMMUNICATION , KBA , BC-JAS-SEC-UME , User Management Engine , BC-CST-GW , Gateway/CPIC , Problem