When manually executing a workflow using Run with payload in the new Azure Logic Apps designer, the payload editor currently enforces JSON input and does not allow specifying a different Content-Type.
This means workflows that expect non-JSON payloads, such as application/xml or text/xml, cannot be manually executed from the designer, even though they are fully supported at runtime.
📝 One-Minute Brief
The new Azure Logic Apps designer restricts Run with payload to JSON-only input, preventing manual execution of workflows that expect non-JSON content types (such as XML), even though those payloads are fully supported during normal runtime execution.
What was tested
A minimal workflow was created that expects an XML payload (application/xml) and performs a simple validation.
- The workflow runs successfully when invoked externally with an XML payload.
- The same workflow cannot be executed using Run with payload in the new designer, as XML input is rejected, and the Content-Type cannot be overridden.
Observed behaviour
Classic Designer
Allows manual execution with raw XML and custom Content-Type.
New Designer
Enforces JSON-only input and provides no option to define request headers.
External Call (Postman)
Sending XML with Content-Type: application/xml executes successfully, even while authoring the workflow in the new designer.
This confirms that the limitation is UI-specific and not related to the Logic Apps runtime.
Current workaround
For workflows that depend on non-JSON payloads, testing currently requires executing the trigger via an external tool (Postman, curl) or falling back to the classic designer.
Suggested improvement
Allow “Run with payload” to support:
- Selecting a Content-Type
- Providing a raw payload editor based on the selected type (JSON, XML, text)
This would enable realistic manual testing without leaving the authoring experience!
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