Hi Hedi,
Can you see the detail SQL error message from pop-up window?
If you can, you may see the information like this
"System.Data.SqlClient.SqlException (0x80131904): Violation of UNIQUE KEY constraint 'xxx'. Cannot insert duplicate key in object 'xxx'. The duplicate key value is (031a67e6-4809-e911-a96e-000d3a370868, CAMX-20181113-0000000288)".
You need to remove the records with this duplicate key.
If you could not see the detail error message, please submit a service ticket to Microsoft Dynamics support. Then the engineer can find the related exception details from the traces.
Thanks,
Wei