Zapier and Unbounce - HubSpot forms returning 400 bad request


Hi there,

We use Unbounce and had previously been using the native Unbounce > HubSpot integration within their product, but were constantly getting integration errors.

Last week, I switched to using a Zap instead to see if it would resolve the issue. We had 1000 leads come in over the weekend, and most of them made it through the Zap and into HubSpot.

However, we had about 90 tasks in Zapier that returned the 400 Bad Request error. When I try to replay the task, it returns the same error each time. This means about 1 in 10 of our leads are not getting into our HubSpot database. Screenshot from Zap below:

This is the same error that we were getting in the Unbounce integration.

We cannot continue to lose 10% of our leads. Please help!


@Torie_DeJong These integrations were build by Unbounce and by Zapier. They would be the best places to dig into why this is happening. HubSpot would not have access to any of the logs as it is not our integration.


I did some detective work and discovered that it is not Unbounce or Zapier that is causing the issue.

The HubSpot form in question had the ‘Block free emails providers’ button checked. When I looked through the submissions that were returning a 400 error in both Unbounce and Zapier, all of them were from Hotmail or Yahoo domains.

HubSpot was rejecting them because the box was checked - even though they were submitted via the API. As soon as we unchecked the box in HubSpot, the submissions stopped returning the error.

It may we worth updating your documentation to reflect this, or updating your error codes to tell people why the request was rejected.


@Torie_DeJong Thanks for the heads up. Can you show me the actual error body you were receiving? I am curious to see what it said.



So the only information that Zapier gave us was: returned (400) Bad Request and said nothing”

What we got from Unbounce was:
“Request Error: HTTP Code: 400 Bad Request - Message:”

So in both cases, a 400 but without any sort of message detailing why.

Hope that helps!


@Torie_DeJong Thanks, Those are the messages that Zapier and Unbounce decided to show you. We have a more verbose error body that both of them would have received when they hit our APIs, they just decided not to pass along the information to the user.

Thanks for the info