Updated Cornerstone and Preview will not load, Website looks completely different and "Critical Error" is showing

Hi, I recently updated Cornerstone on a website from 2019. I’m now having multiple issues as follows:

  • Cornerstone is showing “The preview could not load due to iframe…”
  • The website is displaying completely different to the way it was designed. Was full width, had a Rev Slider, various sections and a form at the base - none of which are showing up now.
  • “There has been a critical error” is stated on the webpage (see attached)

Can you tell how to get the site back?

Hi @alandoyle,

Thanks for reaching out!

It is hard for us to determine the issue without the error log. Would you mind sharing your admin credential and FTP access so that we can check it? To do that, 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.

Thank you.

Hi @alandoyle,

For some reason, your website is throwing 500 error and 500 error is about the server. In the meantime, I suggest that you contact your hosting provider for further support and once it is back, please let us know.

Thank you.

Thanks. I have contacted them and I’m currently waiting on their reply. Back to you soon. Thanks.

Hello @alandoyle,

I am another staff, I checked your site it is not working please let us know when it is working.


It looks like the site was compromised. This has now been corrected by my hosting company. Can you see if you can get in now?

Hi Pavle,

I think your site is not accessible outside U.S?

Please do the following first:

  • Your WordPress is outdated (5.3.8), please update that to the latest version (5.8)
    Updating WordPress

  • Your PHP version is 7.2, please update that to the minimum recommended version of PHP 7.4 (please ask your hosting how you can upgrade PHP version).

  • If the site has any internal caching features please clear those.

After doing that and if the issue persists, please do testing for a plugin conflict.

Let us know how it goes,

After talking with my hosting company it looked like the site was compromised in some way. They fixed this issue regarding the wp-config.php file. I then followed ur instruction to update the PHP and Wordpress versions and it looks like this has now fixed the issue.

Thanks for your help.

Hi Pavle,

Glad to know that everything is fixed now.


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