3398181 - RFC-Error: Invalid substring access: Length 0 - Focused Build

Error when uploading URL to Test Case or when opening a Test Case in Test Step Designer App:

RFC-Error: Invalid substring access: Length 0\{ "message": "HTTP request failed", "headers": \{ "Content-Type": "application/json;charset=utf-8", "Content-Length": "761", "DataServiceVersion": "1.0" }, "statusCode": "400", "statusText": "Bad Request", "responseText": "\{\"error\":\{\"code\":\"SY/530\",\"message\":\{\"lang\":\"en\",\"value\":\"RFC-Error: Invalid substring access: Length 0\"},\"innererror\":\{\"application\":\{\"component_id\":\"SV-SMG-OST-FB\",\"service_namespace\":\"/SALM/\",\"service_id\":\"TM_TS_DESIGNER_SRV\",\"service_version\":\"0001\"},\"transactionid\":\"XXX\",\"timestamp\":\"XXX\",\"Error_Resolution\":\{\"SAP_Transaction\":\"Run transaction /IWFND/ERROR_LOG on SAP Gateway hub system and search for entries with the timestamp above for more details\",\"SAP_Note\":\"See SAP Note 1797736 for error analysis (<a href="https://service.sap.com/sap/support/notes/1797736)">https://service.sap.com/sap/support/notes/1797736)\"},\"errordetails\":[\{\"code\":\"RFC_FAILURE\",\"message\":\"RFC-Error: Invalid substring access: Length 0\",\"propertyref\":\"\",\"severity\":\"error\",\"target\":\"\"}]}}}" } 

 "Image/data in this KBA is from SAP internal systems, sample data, or demo systems. Any resemblance to real data is purely coincidental." 

• SAP Solution Manager 7.2
• Focused Build 2.0

Test Management, SM_WORKCENTER, Fiori. , KBA , SV-SMG-OST-FB-TWB , Test Management , Problem