Preview can not load due to iframe response being incomplete

Support
#1

Hello there,

I am gtting this whenever I try to edit my homepage. No other page on my website is having these issues.

“The preview could not load due to the iframe response being incomplete. This is most often related to a plugin conflict, or customizations introducing a PHP error.”

Origin URL: https://shepherdstage.wpengine.com
Preview URL: https://shepherdstage.wpengine.com/

I have deactivated plugins on the site that would impact the homepage and haven’t had any luck. I checked, and the PHP on the site is up to date. This issue started happening after downloading the new version of cornerstone (which I had an issue with but received support and it worked) Assistance would be greatly appreciated!

The login credentials to the site will be posted in a secure note below. Thank you!

#3

Hi Jody,

By withdrawing the post, I believe you already have resolved the issue. If the issue still existed, you can let us know. I have also checked your website with the given credentials and found the Page Builder loading the preview properly.

Thanks.

#4

Hello! No, I withdrew a post with the site login info because I posted it publically by accident.

When I try to edit the homepage with Cornerstone, it is still giving me the attached error message.

Screen Shot 2021-08-23 at 10.39.00 AM
Screen Shot 2021-08-23 at 10.39.00 AM1258×564 35.1 KB

#5

Hi @JodyGreene,

Thank you, we were able to login and see the error. There is some form of fatal PHP error preventing the preview from loading, but we can’t tell what is triggering it yet. Could you please enable WP_DEBUG in wp-config.php? You can do this by setting it to true like this:

define( 'WP_DEBUG', true );

That should let us see a detailed error message. Thank you!

#7

Like many of your users, we didn’t build the site offline, we built it directly on Wordpress using the interface provided by the theme. When we try to edit the wp-config.php via Filezilla to edit the wp-config.php, we are getting a critical error, screenshot attached. Is there something else I should be doing, or is there another way for you to figure out what’s happening?

#8

Here is the screenshot from Filezilla

Screen Shot 2021-08-23 at 4.46.27 PM
Screen Shot 2021-08-23 at 4.46.27 PM788×450 151 KB

#9

Hi @JodyGreene,

WP Engine should allow that file to be edited, but that FTP log indicates a permission error. You might need to ask them to help enabled WP_DEBUG if you can’t access it.

#10

Gotcha- reached out to wordpress and they enabled WP_DEBUG and cleared our server cache.

#11

Thanks @JodyGreene,

I checked your current site info (https://shepherdstage.wpengine.com/wp-admin/site-health.php?tab=debug) and it looks like WP_DEBUG is enabled, but WP_DEBUG_DISPLAY was explicitly disabled (should be on by default). This is common on production sites, because all the errors go into a log file instead. It shouldn’t be needed on a staging site since we want to find errors instead of suppress the messaging.

#12

Thanks @alexander, just called them back and they said they set WP_DEBUG_DISPLAY to true

#13

Hey Jody,

It is the custom Recent Post shortcode in your child theme that is causing the issue. I activated the parent theme and the builder works (see screenshot in the secure note).

You might have gotten the custom code in our forum but you need to delete it now as it causes an issue.

Please use a Post element to display posts in the new version of X and Cornerstone.

Thanks.

#14

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