Hello @sanchezTJUK,

As a quick sanity check, to eliminate the possibilities of the RIC or code being mistyped or mis-pasted, I have just tested the same request with Postman tool :

{
    "ExtractionRequest": {
        "@odata.type": "#ThomsonReuters.Dss.Api.Extractions.ExtractionRequests.HistoricalReferenceExtractionRequest",
        "ContentFieldNames": [
            "RIC",
            "Start date",
            "Change Date",
            "Expiration Date"
        ],
        "IdentifierList": {
            "@odata.type": "#ThomsonReuters.Dss.Api.Extractions.ExtractionRequests.InstrumentIdentifierList",
            "InstrumentIdentifiers": [
                {
                    "Identifier": "LGOTJ1",
                    "IdentifierType": "Ric"
                }
            ],
           "ValidationOptions": {
                "AllowHistoricalInstruments": true
            },
            "UseUserPreferencesForValidationOptions": false
        },
        "Condition": {
            "StartDate": "2012-01-01T00:00:00.000Z",
            "EndDate": "2021-04-28T00:00:00.000Z"
        }
    }
}

I have valid result:

{
    "@odata.context": "https://hosted.datascopeapi.reuters.com/RestApi/v1/$metadata#ThomsonReuters.Dss.Api.Extractions.ExtractionRequests.ExtractionResult",
    "Contents": [
        {
            "IdentifierType": "Ric",
            "Identifier": "LGOTJ1",
            "RIC": "LGOTJ1",
            "Start date": null,
            "Change Date": "2020-04-08",
            "Expiration Date": "2021-04-12"
        },
        { 
...

This aligns with your understanding of the issue you face being intermittent. However, to me this does not clarify if it is due to potential connectivity interrupts, bandwidth or service outages. Especially as you report this as a common happening, this does not add up, for me.

The way I see it, it would be most useful, exactly when you face the issue, and it is reproducible, at least on your side, to:

1. To review any potential service outages in progress via My Refinitiv Service Alerts. I personally always "Include resolved" as I wish to know if my issue has been resolved recently.
2. If negative, investigate with your local network team if there are any outages in progress that they are aware of that are related to your network and internet connectivity.
3. If negative, open a support ticket via Refinitiv Helpdesk Online to investigate the issue on our side while it is still happening.

If you post on the dev forums, we are glad to help verify the validity of the request, the API usage, but that will likely not be the most effective way to get to the cause of an intermittent issue.

I hope this helps