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Cusom Connectors: Policy templates: expressions not working



In my Custom Connector I need an expression in the policy




I have a query parameter named "content-format"


I defined a policy

- template: Set HTTP-Header

- operation: (my action selected)

- header name: content-type

- header value: @queryParameters(‘content-format’)

- action if header exists: overide

- run policy on: request


If I test my action, the answer from the azure platform is:


  "error": {
    "code": 500,
    "message": "Invalid parameters template. No property names specified in @headers or @queryParameters or @connectionParameters expression",
    "source": "",
    "path": "choose[4]\\when[1]",
    "clientRequestId": "cecfe20d-ddfa-4384-8624-f1aa-63c8c81f"


Where ist my error?



Community Support
Community Support

Hi @Frank37 ,

Please check whether your api has access to the data source.

You could try to switch off authorization and do firewall rule and On-Premises gateway connection for security.

Here's a similar issue for your reference:

What's more, here's a doc about how to use this template that may help you for your reference:



Best regards,

Community Support Team _ Phoebe Liu
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.

Hi Yutliu, the API access to the data source is OK: If I do not use the policy, the action is sent successfully to the server. This error only occurs if I enable the policy for this action (but I need the policy to make the action work correct) Frank

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