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

[omdot]

I’m at my wits end…
A website says “The preview could not load due to the frame response being incomplete. This is most often related to a plugin conflict, or customizations introducing a PHP error.” when trying to edit most of the pages.
I tried deleting all caches, in browser and on the server. Tried different browsers, different OSs, different PHP versions, naturally deactivated all plugins, too. The problem doesn’t go away.
Yes, all updates on everything, all brand spanking new.
Naturally, this happens while I’m on vacation on a different continent and only sporadically online and the site has to be edited. Because when else was it supposed to happen, right?
I’ll add a screenshot I succeeded when I put WordPress in debug mode and a URL and credentials in a private reply, if that still is an option.

Thanks in advance,
om.

[tristup]

Hi Om,

Thanks for reaching out.
I have checked your website and found the issue you have described here. Although you have already performed the common issue test, I would like to request you troubleshoot the following common issue once again to help us to recognize the reason.

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

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, please copy your live site to a staging server so we could troubleshoot freely without breaking your live site.
And give us access to 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.

Thanks