The following headers are not accessible within a Function. Avoid developing any code that depends on these headers or their variants.
You cannot interact with the pre-flight OPTIONS request that is sent by browsers. The Runtime client will automatically respond to
OPTIONS requests with
Access-Control-Allow-Headers: *, and pass along all included request headers to the targeted Function (unless they are in the exclusions list above). In addition, the Runtime client allows all origins by returning
Headers and cookies in both incoming requests and outgoing responses are subject to these limits:
If either of these limits is exceeded, your Function will throw a
431 error. The error will include the message
Request headers or cookies too long if the limits are exceeded by a request, or
Response headers or cookies too long if you've constructed a response that exceeds these limits.
This will also generate a Twilio Error 82008.