Cornerstone - Preview could not load due to the iframe response being incomplete

Support
#1

Hello,

I’ve seen a number of forum posts for this issue, but have not had any luck resolving it myself after troubleshooting and am hoping someone from ThemeCo can take a look. We recently left our previous website builder and brought our website with us. We purchased our own Cornerstone license, validated it, and are now getting this error when trying to Edit with Cornerstone. “The preview could not load due to the iframe response being incomplete. This is most often related to a plugin conflict, or customization introducing a PHP error.”

Screenshot (87)
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I have increased the PHP memory limit on our host server, tried in private browsers, cleared the browser cache, and tested a number of our plugins, without being able to solve the issue. We are unable to edit our webpages because of this issue. This persists across all of the pages on our website. We are running Cornerstone 6.1.4.

Any guidance would be appreciated. Thanks in advance!

#2

Hey Sierra,

Thanks for writing in! In most case, the warning message could be troubleshoot with the following:
The error above shows that there is a fatal PHP error which stopped the rendering of the website and you need to follow the steps below:

  • Enable the WordPress debug mode. You might be able to see an error message on the site right away. If not, the error log could reveal where the problem is originating.
  • If you’re using a child theme, try switching to the parent theme to see if that makes a difference. The conflict could be in your customizations.
  • Test for a plugin conflict by disabling all third party plugins except the Cornerstone plugin if you use X. IF the problem is fixed, activate the plugins one by one to find the plugin responsible for the problem.
  • Make sure that you use PHP version 5.6.x or 7.1.x or 7.2.x. Contact your hosting service provider to make sure that you do not have an old version of the PHP.
  • Make sure that you increase the PHP memory limit to at least 512M. Follow the steps mentioned here for more information.

If the above suggestion does not help, we would love to investigate further. You can create a secure note in your next reply with the following info:
– Link to your site
– WP login URL
– WP username
– WP password
– WP Administrator Role
– Confirmation that we can access and make changes to your site

To know how to create a secure note, please check this out: How The Forum Works

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Best Regards.

#3

Would running a newer version of PHP cause the issue? We are running 7.4 according to our host, and don’t have the option to go lower (at least on my end–I could reach out and ask if it’s possible to downgrade to 7.2?)

Thanks for your help!

#4

Hey Sierra,

PHP 7.4 is the stable version of PHP in WordPress. You can check the recommended version here:

Since you are still having the issue. Please give us the following information in a Secure Note.

  • WordPress Login URL
  • Admin level username and password
  • FTP Access

You can find the Secure Note button at the bottom of your posts.

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Thank you.

#5

I just submitted the Secure Note. Thank you so much for your help!

#6

Hey Sierra,

I suspect that the theme you are using is broken because it is missing a closing </body> tag.

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I tried to activate the default WordPress theme and the builder works perfectly.

Is there any chance to contact the author of the theme? and ask for guidance

Hope that helps.

#7

Thank you for this!! I was able to go in and find the problematic theme file, add the missing tag, and Cornerstone is now working for us. We appreciate your help!

#8

Hey Sierra,

You’re welcome! If you have any other concerns or clarifications regarding our theme features, feel free to open up a new thread.

Thank you.

#9

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