HTTP 412: Precondition Failed When Using Forms API


Using C# HttpWebRequest API to submit this. Have everything filled out according to this webpage. Even using Chrome’s Advanced REST Client to manually submit and still have same problem.

Triple checked the HTTP Method=POST, Headers: content-type=application/x-www-form-urlencoded and content-lengthPortal ID, Form ID, message payload using encoding and without, hs_context.

Any ideas what could be wrong? Can share more information individually if someone can help.


@elwyn.thompson are you logging the body of the response? There should be more details in the response message, but usually this will be caused by the email address having a domain that’s in the blocklist.


Thanks for responding David. Here is an output of the response. If there is a private way to share the request with you I can send that too.



Can you message me directly with more details about the request (including the URL and any payload you’re sending)? You can message me by clicking my name or picture, then clicking the message button.


I have been clicking around your name, went to my messages. I have no button for messages anywhere. Do I have the right access?

I can see the welcome message you sent me to the forum. And at the bottom there is a Message with a mail icon but I cannot click it, stays with cursor pointer.