Unable to preview email templates

Question

From the list of email templates, when I click on the Preview link for an HTML email template the pop-up appears but only an iframe shows with "Please click here if you are not redirected within a few seconds." On my original browser window, the admin backend redirects to the same thing (away from the normal admin backend interface).

When I'm editing a template and click the 'Preview Template' button, I get the same thing on a new tab of my browser.

The browser console shows errors that look like this:

"Blocked script execution in ... because the document's frame is sandboxed and the 'allow-scripts' permission is not set.

and also

Refused to execute the redirect specified via ''. The document is sandboxed, and the 'allow-scripts' keyword is not set.

We are in Developer mode, but it also does this in Production mode. It does this with all templates, not just html templates. Is this a known issue and is there a fix?

Answer 1

Ends up, this was happening due to mod_pagespeed settings. The backend admin url was recently changed but the ModPagespeedDisallow url wasn't updated. Setting it to the new admin url eliminated the problem.