Logic app custom headers missing from HTTP request

Question

We have API as an App Service that sends HTTP request to Logic App. The request contains a specific custom header "x-api-key". Starting from the evening of November 13, 2025 this header started missing from the received request in the Logic App's end. There was no deployments of the API or the Logic App that could have caused the issue. It had worked without any issues for years before this. Our Logic App reads the value of this header, but since it is missing now, that operation fails.

Has anyone faced similar problem with Logic Apps?

Answer 1

The issue you're experiencing with the missing custom header "x-api-key" in your Logic App could be related to how Azure Logic Apps handle certain HTTP headers. Azure Logic Apps automatically remove specific headers from incoming requests without warning. According to the documentation, the following headers are omitted:

• Accept-* headers except for Accept-version
• Allow
• Content-* headers except for Content-Disposition, Content-Encoding, and Content-Type (only honored in POST and PUT operations)
• Cookie
• Expires
• Host
• Last-Modified
• Origin
• Set-Cookie
• Transfer-Encoding

While the x-api-key header is not explicitly listed among the omitted headers, it is important to ensure that it is being sent correctly and that there are no other issues in the API or Logic App configuration that might affect its transmission.

If the issue persists, consider checking for any changes in the API configuration or network settings that could have inadvertently affected the header's delivery. Additionally, you might want to inspect the request using tools like APIM inspector trace to see how the request is processed within the Logic App pipeline.

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References:

• Disable checking location headers
• Azure API is returning blank response