2631298 - Error messages "Sorry, a technical error occurred" and "Could not open app" appear when launching CCM workcenter tiles

When opening a Custom Code Management (CCM) tile in the Solution Manager workcenter, you receive an error:

"Could not open app. Please try again later"

OR:

Sorry, a technical error occurred. Please try again later.

{
"requestUri": "/sap/opu/odata/sap/SERVICENAME/$metadata?sap-client=001&sap-language=EN",
"statusCode": 404,
"statusText": "NOT FOUND",
"headers": [],
<code>HTTP/404/E/Not Found</code><message> Service /sap/opu/odata/sap/SERVICENAME/$metadata call was terminated because the corresponding service is not available.The termination occurred in system SOL with error code 404 and for the reason Not found. Please select a valid URL. If it is a valid URL, check whether service /sap/opu/odata/sap/CCM_NAMESPACES_SRV/$metadata is active in transaction SICF. If you do not yet have a user ID, contact your system administrator. </message></error>"
}

SAP Solution Manager 7.2

Could not open app, a technical error occurred, Maintain Owner, namespace classification, service is not available, CCLM, 7.2, Fiori, CCM, Custom code, sm_workcenter, workcenter, application, app, Namespace Classification, error 404, error 403 , KBA , SV-SMG-CCM , Custom Code Management , CA-FLP-FE-UI , SAP Fiori Launchpad User Interface , Problem