Sanford Whiteman

ATTN: Hotfix for broken embedded forms in Firefox 46 (release date April 19)

Discussion created by Sanford Whiteman on Feb 26, 2016
Latest reply on Dec 2, 2019 by Sanford Whiteman

Warning! On the near horizon is a version of Firefox that will break embedded forms.  As I noted in this post, Firefox 46 -- already in-the-wild for folks using Firefox Developer Edition -- is moving into Beta on March 8 and will be released worldwide via auto-update on April 19.


Luckily, your faithful forms guy has a fix you can put in place now to avoid disruption.  Add the following style either in a <style> tag or via an external stylesheet.  If you use an external stylesheet, make sure it loads before forms2.js/forms2.min.js.


#MktoForms2XDIframe {
    visibility: hidden;
    position: absolute;
    display: block !important;


  • The breakage affects forms using the embed code. It does not affect native form objects on Marketo-hosted LPs, but it can affect forms loaded as embeds (in HTML blocks) on Marketo-hosted pages. If you are not sure which method you use, apply the fix.
  • Marketo Support has been made aware of the issue but has not planned an official fix.
  • The change is related to Gecko's reinterpretation of the CSSOM getComputedStyle method. It should be noted that Chrome and IE are not planning to use the same interpretation.
  • If you want more details you can DM me.