Unable to pass runtime parameters when triggering Microsoft Fabric Data Pipeline via REST API – defa

[NuwanAthukorala]

I am trying to trigger a Microsoft Fabric Data Pipeline from a .NET Core Web API using the official Fabric REST API.

The pipeline triggers successfully, but:

• Runtime parameters passed via API are ignored

• Pipeline always uses default parameter values

• In some attempts, the API returns 405 – Method Not Allowed

This issue blocks external orchestration from enterprise applications.

Environment Details

• Service: Microsoft Fabric

• Item Type: Data Pipeline

• Trigger Method: REST API

• Client: .NET Core Web API

• Authentication: Azure AD (Service Principal)

• Token Scope: https://api.fabric.microsoft.com/.default

Pipeline Parameters

Name Type Default Value

batch_no	Int	5050
Accounting_date	String	1990-01-01
process_type	String	E

API Endpoint Used

POST
https://api.fabric.microsoft.com/v1/workspaces/{workspaceId}/items/{pipelineId}/jobs/instances

.NET Core Code

var requestBody = new
{
parameters = new Dictionary<string, object>
{
{ "batch_no", 4021 },
{ "Accounting_date", "2025-01-01" },
{ "process_type", "E" }
}
};

var url =
$"https://api.fabric.microsoft.com/v1/workspaces/{workspaceId}/items/{pipelineId}/jobs/instances";

using var client = new HttpClient();
client.DefaultRequestHeaders.Authorization =
new AuthenticationHeaderValue("Bearer", accessToken);

var response = await client.PostAsJsonAsync(url, requestBody);

Actual Behavior

The pipeline starts successfully when it is triggered through the REST API. However, when checking Fabric Monitor → Run → Parameters, the values shown are always the default values defined in the pipeline. The parameters batch_no, Accounting_date, and process_type do not change based on the values passed from the API. This means the runtime values sent from the external application are ignored. In some attempts, the same API call also returns a 405 Method Not Allowed error.

Expected Behavior

The pipeline should receive and use the runtime parameter values passed through the REST API. When checking Fabric Monitor → Run → Parameters, the values should reflect the values sent from the API, such as batch_no = 4021, Accounting_date = 2025-01-01, and process_type = E.

Troubleshooting Already Done

The pipeline item type has been confirmed as a Data Pipeline. Parameter names have been checked to ensure they are case-sensitive and match exactly. All query parameters were removed from the URL, and the correct Fabric REST endpoint was used. The access token was generated with the correct Fabric scope. The same request was tested using Postman, and the pipeline was also tested manually in the Fabric UI, where parameters work correctly.

Questions for the Fabric Team

Is triggering a Fabric Data Pipeline with runtime parameters through the REST API fully supported? Is there a different request body or payload format required to pass parameters correctly? Are there any known issues or limitations related to runtime parameters? Is there an alternative supported API for passing parameters from external systems?

Impact

This issue prevents proper external orchestration of Fabric pipelines using APIs or schedulers. It also blocks enterprise system integrations and makes dynamic, batch-based pipeline execution difficult to implement.

Request

I kindly request clarification or confirmation from the Fabric engineering team regarding the correct API usage for parameterized pipeline execution. Any information about known limitations or future roadmap updates related to this functionality would be greatly appreciated.

[v-echaithra]

Hi @NuwanAthukorala ,

Thanks for the detailed investigation and for sharing the repro steps your findings align with the current behavior of Microsoft Fabric Data Pipelines.
At this time, passing runtime parameters to Fabric Data Pipelines via the REST API is not supported, it’s a current platform limitation. Even though the API accepts the request and the pipeline run is created successfully. Fabric currently does not apply these parameters to the pipeline run execution.
Even though Fabric accepts the parameters block in the API call, the pipeline still uses default values inside the pipeline execution and UI monitoring.

To clarify the REST endpoint (POST /v1/workspaces/{workspaceId}/items/{pipelineId}/jobs/instances) is correct and does trigger the pipeline run.

Seeing the execution in Fabric Monitor confirms that authentication, permissions, and item type are valid.
However, runtime parameters provided in the request body are currently ignored, and Fabric always uses the design-time default values defined in the pipeline. While the API contract exposes a parameters payload, parameter binding is not yet implemented for Data Pipelines.
Regarding the intermittent 405 - Method Not Allowed responses, this is a known platform side behavior and can occur due to backend routing, regional rollout differences, throttling, or when triggering the same pipeline in quick succession. It is not related to the request payload or parameter format.

Short term Workaround, If you must pass runtime parameters in API calls today, use a notebook instead of a data pipeline, since notebook REST API supports parameters now (preview).Runtime parameter support for Data Pipelines via REST is a known gap, and enhancements are planned, though there is no public ETA at this time.

Hope this helps.
Chaithra E.