Pro page builder not loading lessons from learndash Vs High (100%) CPU Usage


So When I try to edit the lesson (from learndash plugin) using PROpage builder the pre-loader keeps spinning and not loads the preview page. Apparently the issue only exists when I try to edit LESSONS, so I can edit pages, courses etc. but no lessons. I know this was working before because I’ve edited using the previous theme version.

I dont know if this issue is related with the High CPU Usage (100%!!!) from my shared host, yes while the pagebuilder was trying to load I check the CPU usage increasing the percentage like a beast. I have open ticket the host to check their feedback.

Can you please help me with your insights?

Hi Jujiz,

There might be some different reason behind it, I would like to suggest troubleshoot the following common issue to help us to recognize the reason.

1.Theme Related Issue
2.Plugin Conflict
3.Theme Update related issue
4.Child Theme Related issue
5.CSS/JS Customization
6.Disabling Cache

If you discover that an issue is coming from a custom code or 3rd party plugin, kindly consult with a developer or contact the plugin author. Please note that we do not provide support for custom codes and 3rd party plugins.
If none of the above helps and you are still getting the issue, please copy your live site to a staging server so we could troubleshoot freely without breaking your live site.
And give us access in the secure note including:

– WordPress Site URL & Login URL
– WordPress Admin username/password

To create a secure note, click the key icon underneath any of your posts.


This is now urgent to me…

I have troubleshoot and I still getting the issue.
I was thinking that it could be of a plugin conflict or the code that I have on the child theme but after the troubleshoot I dont know what could be the reason.

any news about this issue?
please, need your assistance

Hi @juliana,

I’ve checked your site and it looks like there’s an issue with your HTTPS configuration. If you open the browser developer tools you can see this error in the console:

Uncaught (in promise) DOMException: Failed to construct 'Worker': Script at '' cannot be accessed from origin ''.
    at i (

The worker script gets loaded from the app script. Notice how one of them is http instead of https? This could mean that you have a system that is trying to automatically rewrite http to https instead of it being saved as the WordPress site URL. I see you have the Really Simple SSL plugin active, but it doesn’t seem to be fully configured.

I would recommend starting there and getting your site fully running on HTTPS before continuing. Thanks!

Hello @alexander
I checked Really Simple SSL, the only missing configuration was the 301 Redirect. WP Cloudflare Super Page Cache was also missing configuration, maybe because you where troubleshooting a Plugin Conflict.

“If you open the browser developer tools you can see this error in the console” - I dont see this error. Can you check if its ok now?

hello @alexander

This is my job and I need this tool working soon as possible, I am here looking for a reply, please advice

@tristup need assistance! I am almost 10days stucked here…

Hey Jujiz,

Please try completely disconnecting Cloudflare from your site so we can clearly see where the issue is coming from. I see a 524 and an admin-ajax error which indicates there’s a problem with your server.


Please also Increasing Php Memory Limit

Please also give us FTP or cPanel access to your server.


hello @christian I already report to my host.

1 - I change the nameservers of the domain to be the ones from the server.
2 - About the PhP memory limit, I already had this code: define(‘WP_MEMORY_LIMIT’, ‘512M’);
at wp-config (see attached image

Regarding Cloudlare, I didnt change the nameservers, I switch Cloudflare to Development Mode in order Temporarily bypass the cache and see changes the origin server in realtime.

Please need your feedback

@christian Im sorry but this is insane, I cant do my work… I dont know if you are giving priority to this issue. I guess I should Restore a backup from the your previous update? let me know any news…

Hey @juliana,

Thanks for testing. We answer threads from the oldest to newest that is why you must not post succeeding replies as it will move your thread to the newest queue and we currently are receiving a high volume of inquiries which usually happens when we release a major update so it takes some time to reach your thread.

Since the issue is prohibiting you from working, yes, please restore a backup of your site. If you wish us to continue investigating, please copy your live site to a staging server and we’ll check there. This is also the recommended way for us to investigate as there’s no risk of breaking your live site.


I’m getting this error now:

“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.”

I have two websites working on LearnDash and One was working while the other was not. So that was a goo opportunity to figure out what’s gone wrong.

So I began to update the plugins on the working website one by one and they all worked fine. But as soon as I upgraded from 4.0.10 to 4.1.5 on the pro theme, it broke the site.

So not sure what changed between the two issues, but something between them is causing it.

Where can I download 4.0.10?

Hello @muaawiyahtucker,

Thanks for writing to us.

Unfortunately, we don’t provide the older version of the theme. As far as your issue concern I would suggest you please follow my colleague @tristup suggestion. In case if it doesn’t work for you, I would suggest you open a new thread and provide your details with the credentials of your site.

It would be best if you could copy your live site to the staging server so that we can investigate your settings without breaking your live site.


I did make a separate post.

I have cloned my website to a test path, so how to I give you details about logging in so you can see what’s going wrong?

Sorry, but making a test subdomain version was just long, as I was having problems issuing the SSL certificate. Needless to say, it’s quite urgent that I get my hands on a version 4.0.10 or 4.0.11, as I cannot edit my website without it. I will definitely investigate how to fix it with the most recent version and even chase it up with maybe LearnDash as well, but until then, I cannot update the website or release new content to my customers without 4.0. Could an exception be made here considering the solution is that simple?

Hello @muaawiyahtucker,

Marc has responded to your email and also your thread. To better assist you with your issue, kindly provide us access to your site so that we can check your settings. Please create a secure note in your OWN thread 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

Thank you.

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