Fabric - Create Reports model via Microsoft Fabric API

Hello Everyone,

I'm using the Microsoft Fabric REST API to programmatically deploy a report to a workspace. The semantic model already exists and is verified in the workspace.

I'm sending a POST request to (https://api.fabric.microsoft.com/v1/workspaces/${groupId}/reports😞

const reportCreated = await axios.post(
      `https://api.fabric.microsoft.com/v1/workspaces/${groupId}/reports`,
      {
        displayName: reportName,
        description: "A report description.",
        definition: {
          parts: [
            {
              path: "definition.pbir",
              payload: reportDefinationBase64,
              payloadType: "InlineBase64",
            },
            {
              path: "report.json",
              payload: reportBase64,
              payloadType: "InlineBase64",
            },
            {
              path: ".platform",
              payload: platformBase64,
              payloadType: "InlineBase64",
            },
          ],
        },
      },
      {
        headers: { Authorization: `Bearer ${creds.access_token}` },
      }
    );

My defination.pbir 

{
  "version": "4.0",
  "datasetReference": {
    "byPath": null,
    "byConnection": {
      "connectionString": "Data Source=powerbi://api.powerbi.com/v1.0/myorg/${org};Initial Catalog=MERINAPDTSalesSemanticModelLN;Integrated Security=ClaimsToken",
      "pbiServiceModelId": null,
      "pbiModelVirtualServerName": "sobe_wowvirtualserver",
      "pbiModelDatabaseName": "e0f124a7-cdc7-4f33-941e-8afa1bf26313",
      "connectionType": "pbiServiceXmlaStyleLive",
      "name": "EntityDataSource"
    }
  }
}

✅ Confirmations:

• The semantic model is deployed and exists in the workspace.

• All paths and files (definition.pbir, report.json, .platform) are correctly encoded and valid.

• The API request is authorized and reaches the endpoint

   

  ❌ Problem:

  I consistently receive the following error:
  Report Workload failed to import the report with report id 428d197b-abee-4ac0-a92f-d20be0839ba3. 
  
  Any ideas on what might be going wrong? Is there a hidden dependency or format requirement for .pbir or report.json when using byConnection?