The preview could not load due to the iframe response

[eugenetim]

Hello. I didn’t updated website 3-4 weeks. Today I’ve tried to modify the page using Cornerstone and get message: "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: http://www.fotolandscape.com
Preview URL: http://www.fotolandscape.com/?page_id=13336".
I’ve seen similar message in December on long pages sometimes (it was “Preview was unresponsive after loading”). The problem was connected with slow server performance. I’ve switched to DigitalOcean and everything works fine. Now I obtain such message even on empty pages.
I’ve updated theme and Cornerstone to latest versions. But no luck.
I’ve tried to enable ‘debug’ mode in WP, but didn’t get any errors connected with this problem.
Please check my website www.fotolandscape.com. Any ideas?

[mldarshana]

Hi There,

Thanks for writing in! Checked your server configurations and everything seems to be alright.

• PHP v5.6.33
• Memory limit 512MB

Couple of things I would suggest you to do. Install the following plugin and configure (https://wordpress.org/plugins/error-log-monitor/), so that it will record any error and you can see the log file within your WordPress dashboard.

If you don’t see any errors, try re-installing your X theme & Cornerstone plugins so that if you have any missing files or corrupted files, it will fix the issue.

You can simply switch to another theme, then delete X theme and re-install it through Appearance -> Themes section. Similarly you can delete Cornerstone plugin through your WordPress plugins section and then head over to X -> Validation section and wait for few seconds to install it automatically.

Let us know how it goes.
Thanks!

[eugenetim]

Thank you for reply. I’ve solved part of the problem with _“iframe response being incomplete” message. The reason was corrupted WP core files. I just reinstalled Wordpress and make changes in config file.

But now I’ve got another problem. During loading page in Cornerstone in 95% cases I see message: "The preview was unresponsive after loading. This is most often related to a plugin conflict or aggressive page cacheing".

And when this message appears on the screen I see loading of page content on background. After pressing “Try again” button content refreshes one more time and I may start editing. Nevermind how long my page is. I see this message even if page consists of one section just with text.

UPDATE: On long pages I’ve get “preview was unresponsive after loading” message forever and can’t edit page.

[rad]

Hi there,

The message will appear on slow pages, and yes, it’s usually happening on pages with longer content. And the loading speed of a long content depends on the processing power of your host environment, and also depends on maximum post size allowed by your host.

Please check this https://www.drupal.org/docs/7/managing-site-performance-and-scalability/increase-upload-size-in-your-phpini

You may also contact your hosting provider to see if they can improve the loading speed for longer page.

Thanks!