Content-type header not being sent from web activity in ADF v2 - azure-data-factory

Question

We use a web activity in ADF v2 to interact with the Azure Automation Account API (Job creation) based on this specification https://learn.microsoft.com/en-us/rest/api/automation/job/create
Since 09-04-2020 the PUT web call isn't working because the header "Content-Type : application/json" is not being sent. The pipeline that contain the activity hasn't changed in months, just stopped working suddenly with the error:
Operation on target Automation - AAS Processing failed:
{
"code": "UnsupportedMediaType",
"message": "{\"Message\":\"The request entity's media type 'text/plain' is not supported for this resource.\"}"
}
But the input request for the pipeline, does include the header:
{
"url": "https://management.azure.com/subscriptions/xxxxx/resourceGroups/xxxxx/providers/Microsoft.Automation/automationAccounts/xxxxx/jobs/55a1bfa2-340c-4120-ba42-43df9e9f4e14?api-version=2017-05-15-preview",
"method": "PUT",
"headers": {
"Content-type": "application/json"
},
"body": "{\"properties\":{\"runbook\":{\"name\":\"aas-masterdata-management\"},\"parameters\":{\"Masterdata_Table\":\"RLS\"},\"runOn\":\"\"}}",
"authentication": {
"type": "MSI",
"resource": "https://management.azure.com"
}
}
I've tried so far:
Recreate the pipeline
Test in a different ADF instance
Delete and redeploy all the pipelines
Delete the header
Change the header to lowercase, uppercase, etc
Add the header twice
Use a self-hosted integration runtime
Test in Debug mode
Any of these tests have been successful. Just for confirmation, I've run the same call from Postman and from the rest api debug tool included within the Api documentation, both worked perfectly, if I set the content header to text/plain in postman or in the web tool I get exactly the same error than in ADF v2. It seems that something has changed in the web call activity of ADF v2 that hardcodes the content header as "text/plain" somehow.
Is someone facing this same issue ? As I said, pipeline definition hasn't changed in months, just stopped working few days ago.

Answer 1

Answer from the ADF platform team:
I got update from Product team that using "Content-Type" instead of "Content-type" will resolve this issue. This can be referred in the documentation
It seems that they accepted "Content-type" before, as it was working several months with that config, but not anymore. So if someone experiences the same problem, here is the answer.
Thanks.

Answer 2

If you are creating the ADF webhook activity using a bicep file, I found this approach works to set the Content-Type in the header parameter.
Define a string variable with the hyphenated Content-Type name
Use string interpolation to include the variable in the headers param
var contentType = 'Content-Type'
activities: [
{
dependsOn: []
description: ''
name: 'MyWebHook'
userProperties: []
type: 'WebHook'
typeProperties: {
body: {
value: '#json(concat(\'{"data":"\',item().data,\'","startTime":"\',item().startTime,\'","endTime\\":"\',item().endTime,\'"}\'))'
type: 'Expression'
}
headers: {
'${contentType}': 'application/json'
}
method: 'POST'
reportStatusOnCallBack: true
timeout: '00:10:00'
url: listCallbackURL('${logic_app_id}/triggers/manual', '2016-10-01').value
}
}
]