3279215 - Reverse Invoke (RI) with cascade of SAP Web Dispatchers with External server does not work

The url of external server with (first) SAP Web Dispatcher which is configured with Reverse Invoke (RI) does not work. In this scenario, there are two SAP Web Dispatchers cascaded and configured with Reverse invoke to connect with external server.

The url fails with "503 Service Unavailable" error.

Trace of (first) SAP Web Dispatcher configured for Reverse Invoke (RI) will show below error:

dev_webdisp:

[Thr 139729605662464] HTR: HTTP version = 1001.
[Thr 139729605662464] HTR: connection = 'keep-alive'
[Thr 139729605662464] HttpGetRouteTargetSystem: using existing SID=<SID>
[Thr 139729605662464] HttpGetRouteTargetSystem: SID='<SID>'
[Thr 139729605662464] HTR: routing destination type = ICF/ABAP .
..
[Thr 139729605662464] Request could not be dispatched to system <SID>: no valid server found. Check connectivity to backend servers. [http_plg.c 10280]
[Thr 139729605662464] role: Server, protocol: HTTPS, local: <local Server IP>:<port>, peer: <remote IP>:<port>
..
[Thr 139729605662464] PlugInStopConn: role: Server(1), error: No server available(-52), write_err: 1
[Thr 139729605662464] PlugInStopConn: write error response
[Thr 139729605662464] HttpPlugInWriteErrorText: return static error for "No server available" (-52)
..
[Thr 139729605662464]   HTTP/1.0 503 Service Unavailable

SAP Web Dispatcher

reverse invoke, EXTSRV, wdisp/system_XX, web dispatcher, kernel,503, RI, cascade , KBA , BC-CST-WDP , Web Dispatcher , Problem