We use Google Tag Manager to setup form submission tracking for most of the sites we build and manage for our clients and I noticed something strange happening the other day when testing some tracking implementations.
We use a basic form submit trigger inside Google Tag Manager to listen for successful form submissions on any form that contains "hsForm_" inside its id="" attribute. This works perfectly fine for HubSpot forms that redirect to another page using the redirectUrl option for the embedded forms, however it stops working when using the inline message functionality. When debugging using chromes developer tools I saw this new warning appear:
I searched around a bit and found a few Stack Overflow conversations about changes made inside Chrome 56 that seems to be related to this issue:
When this error appears - the form submission does not make its way into the HubSpot contacts database, however the front-end appearance of the form still operates as if it did (hides the form and shows the submit message etc...).
Its even more bizarre that this only seems to happen if a form submit trigger is set inside Google Tag Manager - which is a large issue considering it is a widely used tracking solution not only for our client base but the web in general.
Any thoughts here? I searched the forums for this error message and was not able to find anything anywhere.
I would be happy to provide a test GTM container export to aid in debugging this issue if needed.