Forms API Stopped Working


We’ve had this VB.NET code running for almost 3 years. Today, the data is no longer going to HubSpot. Any thoughts as to what could be the issue? Has Hubspot changed something?

 'Build Endpoint URL
    Dim strEndpointURL As String = String.Format("{0}/{1}", intPortalID, strFormGUID)

    'Setup HS Context Object
    Dim hsContext As New Dictionary(Of String, String)
    hsContext.Add("hutk", strHubSpotUTK)
    hsContext.Add("ipAddress", strIpAddress)
    hsContext.Add("pageUrl", strPageURL)
    hsContext.Add("pageName", strPageTitle)

    'Serialize HS Context to JSON (string)
    Dim json As New System.Web.Script.Serialization.JavaScriptSerializer
    Dim strHubSpotContextJSON As String = json.Serialize(hsContext)

    'Create string with post data
    Dim strPostData As String = ""

    'Add dictionary values
    For Each d In dictFormValues
        strPostData &= d.Key & "=" & Server.UrlEncode(d.Value) & "&"

    'Append HS Context JSON
    strPostData &= "hs_context=" & Server.UrlEncode(strHubSpotContextJSON)

    'Create web request object
    Dim r As System.Net.HttpWebRequest = DirectCast(System.Net.WebRequest.Create(strEndpointURL), System.Net.HttpWebRequest)

    'Set headers for POST
    r.Method = "POST"
    r.ContentType = "application/x-www-form-urlencoded"
    r.ContentLength = strPostData.Length
    r.KeepAlive = False


Hi @bcote

There haven’t been any recent changes that should affect this. Are you getting any response at all from HubSpot for those submissions?


Hi, I had a similar problem. All my form API submissions stopped working on 18 Oct 2016 without any changes to my code.
After much investigation, I found this to be caused by the lack of Content Length header in the request. Before 18 Oct 2016, requests without a Content Length header were accepted by the Hubspot Form API but after 18 Oct, requests without that header all fail!

Apparently, the content length issue was most likely related to a change made by Hubspot for routing traffic to through Akamai (411 Length Required)

The weird / worrying thing is that, now that I have added the Content-Length header, the api is still not storing my forms correctly. All fields are stored except my last form field, which is being truncated (by 5 characters). My guess is that this is caused by wrong encoding or content length interpretation by the HubSpot Form API but I’m still waiting on HubSpot support to investigate this further