onSuccess handler to follow-up page has stopped working

[pmann-elementum]

Does anyone know why my handler has stopped working? I made a change to the number of fields on the form and it seems to have broken it. 

The form settings have a fallback page of a home page redirect, but this usually interrupts it, but has stopped doing so and filling in the form takes you to the home page now. 

<script src="//MYSITEHERE.com/js/forms2/js/forms2.min.js"></script>
<form id="mktoForm_1058"></form>
<script>MktoForms2.loadForm("//MYSITEHERE.com", "465-NDL-037", 1058, function(form) {
    //Add an onSuccess handler
    form.onSuccess(function(values, followUpUrl) {
        // Take the lead to a different page on successful submit, ignoring the form's configured followUpUrl
        location.href = "MYSITEHERE.com/PAGE";
        // Return false to prevent the submission handler continuing with its own processing
        return false;
    });
});
</script>

[SanfordWhiteman]

Link to your actual page, please.

[pmann-elementum]

Thanks!

Page:

https://www.elementum.com/lp/how-your-business-can-benefit-from-esm-software/ 

unredacted code:

<script src="//go.elementum.com/js/forms2/js/forms2.min.js"></script>
<form id="mktoForm_1058"></form>
<script>MktoForms2.loadForm("//go.elementum.com", "465-NDL-037", 1058, function(form) {
    //Add an onSuccess handler
    form.onSuccess(function(values, followUpUrl) {
        // Take the lead to a different page on successful submit, ignoring the form's configured followUpUrl
        location.href = "https://www.elementum.com/lp/typ/thank-you-guide-to-esm/";
        // Return false to prevent the submission handler continuing with its own processing
        return false;
    });
});
</script>

[SanfordWhiteman · Accepted solution]

The cause is you have a script you’re injecting via GTM that uses the default Thank You URL:

        a.onSuccess(function(b, c) {
            window.dataLayer.push({
                event: "mkto.form.success",
                "mkto.form.values": b,
                "mkto.form.followUpUrl": c,
                eventCallback: function() {
                    document.location.href = c
                },
                eventTimeout: 3E3
            });
            return !1
        })

This code waits for the Data Layer event to be complete and then redirects to c — the original Thank You.

[pmann-elementum]

Ah, thank you - may I ask how you stepped through the code to find it? Chrome debug tools wouldn't step through the loop accurately enough for me.

Or if you know where these functions are documented more clearly to prevent this happening in the future? 

Thank you, again. 

EDIT: Unfortunately that was not the solution. That code was in place before the issue occurred for about five weeks, and removing it hasn't solved the issue either. 

[SanfordWhiteman · Accepted solution]

---

EDIT: Unfortunately that was not the solution. That code was in place before the issue occurred for about five weeks, and removing it hasn't solved the issue either.

GTM tag absolutely is the cause. Tested by blocking gtm.js from loading entirely.

[pmann-elementum]

Thank you for this, I dug a little deeper and found there was still an recalcitrant tag active I had overlooked - but why it hadn't affected anything until I edited the forms in Marketo Design Studio is a mystery to me. Appreciated.