3129009 - Getting Error Due to Maintenance While Calling C4C OData Service from External System

Using POSTMAN with the GET option, you are trying to fetch opportunities created in C4C and receive below information:

"Dear SAP Cloud for Customer User, Your system is currently unavailable. This is either due to maintenance that was scheduled within your agreed maintenance window. Then please try to access your system a gain after the maintenance window. Otherwise we apologise for the inconvenience. We are currently working to get your system back online as soon as possible."

But there is no current maintenance window, and the issue remains although the system is online.

 SAP Cloud for Customer

1. Go to POSTMAN
2. In the Collection tab select GET for your specific service 
3. Click on Send
4. The system is displaying below message:

"Dear SAP Cloud for Customer User, Your system is currently unavailable. This is either due to maintenance that was scheduled within your agreed maintenance window. Then please try to access your system a gain after the maintenance window. Otherwise we apologise for the inconvenience. We are currently working to get your system back online as soon as possible."

1. Go to POSTMAN
2. In the Collection tab select GET for the opportunity Collection and click Send
3. Go to the tab Headers and select Host <calculated when request is sent>
4. Click Send

Postman; Opportunity; This is Either Due to Maintenance that was Scheduled within your Agreed Maintenance Window , KBA , LOD-CRM-INT-API , OData API (C4C Only) , Problem

SAP Cloud for Customer core applications all versions