MALFORMED_REQUEST_HEADER

The MALFORMED_REQUEST_HEADER error signifies that a request made to the server includes a header that is incorrectly formatted or contains invalid data. This could be due to syntax errors, incorrect header field names, or incompatible header values.

400

MALFORMED_REQUEST_HEADER

Bad Request

Troubleshoot

To troubleshoot this error, follow these steps:

  1. Inspect request headers: Review the headers in your request. Ensure that they are correctly formatted and adhere to the HTTP standard
  2. Validate UTF-8 encoding: Confirm that all request headers, especially cookie values, are valid UTF-8 strings. Non-UTF-8 characters in headers, particularly in the cookie header, often cause this error
  3. Examine Vercel Function behavior: Since this error is specific to Vercel functions, verify the functionality and responses of your Vercel functions. Ensure they are correctly handling request headers and not contributing to malformed responses

Not what you were looking for?

Try filtering the errors by tag, code, or name on the Error Codes page.