Hello Marco,
I was able to remove the opportunity from the account. After removing the opportunity, I was still not able to update the account owner.
Error message from the debug is show below. It says missing read opportunity privilege, but I have already disassociated the Opportunity from Account and I am updating only account owner. Appreciate anything that you could help.
error: {code: "0x80040220",…}}
error: {code: "0x80040220",…}
code: "0x80040220"
message: "Principal user (Id=048417ce-b459-ea11-a811-000d3a31c841, type=8, roleCount=1, privilegeCount=506, accessMode=0), is missing prvReadOpportunity privilege (Id=f7767f74-628d-48b3-a79f-9c6e24fedb69) on OTC=3 for entity 'opportunity'. context.Caller=1375653f-61e0-4dc2-a8aa-ef3c70bad955"
innererror: {,…}
message: "Principal user (Id=048417ce-b459-ea11-a811-000d3a31c841, type=8, roleCount=1, privilegeCount=506, accessMode=0), is missing prvReadOpportunity privilege (Id=f7767f74-628d-48b3-a79f-9c6e24fedb69) on OTC=3 for entity 'opportunity'. context.Caller=1375653f-61e0-4dc2-a8aa-ef3c70bad955"
type: "System.ServiceModel.FaultException`1[[Microsoft.Xrm.Sdk.OrganizationServiceFault, Microsoft.Xrm.Sdk, Version=9.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]"