You are using ODATA and intend to update information on the field Created By for the 'ServiceReqeustCollection' for example, but you receive an error "Update not allowed for properties: CreatedBy".
SAP Cloud for Customer
System Administration Data (Created By, Changed By, Created On, Created By, etc.) is always read-only for any Business Object on the system. If you try to edit these on the UI, it won't be possible as well.
This is the system expected behavior.
2325562 - Frequently Asked Questions on C4C OData Services
Updatable ; Creatable ; Filterable ; Console ; Service Explorer ; metadata , KBA , LOD-CRM-SRP , Service Request Processing , How To