3313391 - SAP Web dispatcher does not connect to the Message Server

Sap Web dispatcher is unable to reach the backend message server, in the dev_webdisp trace you can see errors similar to these:

*** ERROR => IcrIHandleHTTPClientRequest: IctHttpOpenMessage() failed (rc=29) for request (example.sap.com), headerLen (0), contenLen (-1), buffer used (7) [icrxxutil.c  430]
*** ERROR => Read info from XXX message server example.sap.com failed: Internal ICM error(-1), see also SAP note 1528396 [icrxx.c      4318]

Or

*** ERROR => IcrIHandleHTTPClientRequest: IctHttpOpenMessage() failed: Data incomplete(18) for response (target.system:port/msgserver/text/logon?version=1.3), contenLen (-1), buffer used (0) [icrxxutil.c  720]
*** ERROR => Read info from XXX message server example.sap.com failed: Internal ICM error(-1), see also SAP note 1528396 [icrxx.c      4766]

SAP Web Dispatcher

sap web dispatcher, ms/server_port, HTTPS, HTTP, Read info from message server, Internal ICM error(-1), dev_icm,trace, parameter, message server , KBA , BC-CST-WDP , Web Dispatcher , Problem