HTTP Webhook Error 500 when supplying a response expression

[Alain_Jaques]

Hi

I’ve followed the example in the Camunda Academy example but I am getting a server 500 error as soon as I add the Webhook Response expression e.g. {message: “Hello”}. Without the expression I get a successful server response but obviously no body as nothing is configured.

I am running the Camunda Cloud 30 day evaluation.

How do I trouble shoot this? Are there logs viewable?

https://academy.camunda.com/c8-how-to-http-webhook-connector/1565841

[nathan.loding]

Hi @Alain_Jaques - good questions! First, can you attach your BPMN model?

[Alain_Jaques]

Hi @nathan.loding thanks for responding. Attached is the BPMN.
Webhook API Request.bpmn (4.7 KB)

[Alain_Jaques]

This is the successful response with nothing set in the response expression

[Alain_Jaques]

When I add the response expression I then get a 500 error from the API

[nathan.loding]

@Alain_Jaques - I don’t think I’ve seen a 500 error from this before. Here’s one solution to try:

Problem with webhook start event connector response

You could try destroying and creating the cluster! Also be sure to save any secrets you may have defined on the cluster. I’d try checking one more thing in the BPMN’s XML file. If there are any mentions of inbound.responseExpression, please rename them to inbound.responseBodyExpression [edit: in addition to updating the “zeebe:modelerTemplateVersion” value to “10”] Thanks for your patience

I suspect the issue is the same as what the user encountered. Let me know if this fixes it or not, so I can provide this feedback to the product team!

[Alain_Jaques]

@Problem with webhook start event connector response

responseExpression

Thanks I’ll give it a try and let you know the result.

[Alain_Jaques]

Hi… success!!!

The inbound.responseExpression is the issue. When I changed it in the XML editor to inbound.ResponseBodyExpression it works. The downside is that the modeler does not recognise this and does not display the Response expression even though it exists in the XML. If you retype it in the modeler then it reverts back to the inbound.responseExpression and then fails to work until you re-edit the XML.

Camunda people this is a bug you should prioritise to fix. Getting a REST API response is a basic piece of functionality that needs to work effortlessly as per the tutorial and instructions.

[Alain_Jaques]

Update… the easiest fix (as per the referenced Topic above) is to edit the XML and change the TemplateVersion to 10 (mine was 11). This then displays the Response expression correcly too in the Modeler.

zeebe:modelerTemplateVersion=“10”

[nathan.loding]

Hi @Alain_Jaques - thanks for the feedback; and I agree! It will be resolved in the 8.6 release, but it’s difficult to work with until then. I’ve given this feedback to the product teams and they are already working on a way to ensure this doesn’t happen in future release cycles.