Cannot set value for 2 fields at once using OData endpoint in CRM2011 - dynamics-crm-2011

Question

I'm modifying 2 fields on my custom entity, the first field is a lookup field which links to systemuser entity, the second field is simply a two options field.
This is the JSON data I send to Odata end point:
{
"new_saleperson":
{
"__metadata": {"type":"Microsoft.Crm.Sdk.Data.Services.EntityReference"},
"Id":"<My ID>",
"LogicalName":"systemuser",
"Name":"<My Name>"
}
,"new_isenabled":true
}
And the header:
Content-Type: application/json
X-HTTP-Method: MERGE
However, I got the following error:
<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<error
xmlns="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata">
<code>-2147220891</code>
<message xml:lang="ja-JP">The source was not found, but some or all event logs could not be searched. To create the source, you need permission to read all event logs to make sure that the new source name is unique. Inaccessible logs: Security.</message>
</error>
The strange thing is, if I update 1 field at a time, then everything goes as expected. In other word, the following JSON data can set new_saleperson field just fine:
{
"new_saleperson":
{
"__metadata": {"type": "Microsoft.Crm.Sdk.Data.Services.EntityReference"},
"Id": "<My ID>",
"LogicalName": "systemuser",
"Name": "<My Name>"
}
}
And the following JSON data can set new_isenabled to true without any problem:
{
"new_isenabled":true
}
I even tried setting both fields at once, but let new_saleperson be null, and it works:
{
"new_saleperson":
{
"__metadata": {"type":"Microsoft.Crm.Sdk.Data.Services.EntityReference"},
"Id":null,
"LogicalName":null,
"Name":null
}
,"new_isenabled":true
}
It just that setting both fields at the same time, with non-null value is causing error. What am I doing wrong here?
I'm using Dynamic CRM 2011 on-premise.

Answer 1

Is it possible that your SalesPerson Id is not a valid system user? The system will throw an error if you use a GUID that doesn't exist.