3069412 - WD4A fails with "The URL contains no complete domain specification" when open from Cloud Portal/Launchpad Service in BTP

When opening Web Dynpro ABAP application from Cloud Portal/Launchpad Service in SAP Business Technology Platform(BTP), it ends with error:
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500 Internal Server Error
The URL contains no complete domain specification (<IP address or server name> instead of <IP address or server name>.<domain>.<ext>). 
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• SAP Launchpad Service
• SAP Cloud Portal Service
• SAP Business Technology Platform  - BTP

cloud portal, webdynpro abap, wd4a, onpremise s4 hana, s/4hana, s4hana, fiori portal, central launchpad, cFLP, wd app , KBA , EP-WZ-SM , Site Management , BC-WD-ABA , Web Dynpro ABAP , BC-MID-SCC , SAP Cloud Connector On-Demand/On-Premise Connectivity , EP-CPP-NEO-FS , Freestyle sites , Problem