3220573 - Business Application Studio cannot launch Fiori Application due to error 'Failed to register backend for /sap. Check configuration in yaml file.'

Business Application Studio fails to launch SAPUI5/Fiori application due the the following error:

ux-proxy Starting fiori-tools-proxy using following configuration:
ux-proxy proxy: 'http://127.0.0.1:<port>'
ux-proxy ignoreCertError: 'false'
ux-proxy backend : [{"path":"/sap","url":"http://<yourhost>:<port>","client":"<client_id>","destination":"<destnation_id>"}]
ux-proxy ui5: [{"path":"/resources","url":"https://ui5.sap.com","version":"1.65.1"},{"path":"/test-resources'
"1.65.1"}]
ux-proxy debug: ’false’
ux-proxy Backend proxy started for http://<yourhost>:<port> /sap
ux-proxy Used destination: <destination_id>
ux-proxy Failed to register backend for /sap. Check configuration in yaml file,
ux-proxy Error: Request failed with status code 500
A Process Failed With Error
Error Message:
Failed to register backend for /sap. Check configuration in yaml file. Error: Request failed with status code 500

• SAP Business Technology Platform

ux-proxy, sapui5, fiori, yaml, error, failure , KBA , CA-UX-IDE , Tools for developing SAP Fiori applications , CA-BAS-FS , File System,Logging,Operator Clusters , Problem