Updating failed. Error message: The response is not a valid JSON response.

[phpdocs]

Hi,

When i try to update the Page Template from default to full page then i am getting that error "Updating failed. Error message: The response is not a valid JSON response." in WordPress Version 5.3

[phpdocs]

Error screen shot

[SergeyBiryukov]

Hi @phpdocs, welcome to WordPress Trac! Thanks for the report.

Does the issue still happen with all plugins disabled and a default theme (Twenty Nineteen) activated?

[phpdocs]

Hi @SergeyBiryukov, yes same issue with Twenty Nineteen and all plugins are disabled.

[phpdocs]

@SergeyBiryukov recently i checked same issue with posts.

[diquispe]

Same BUG with my site with elementor, disabled themes and plugins with the same error

[ncpr]

Seeing same on one of our 5.3 installations using Twenty Nineteen. Happens when editing posts or pages, in any field as far as we can tell, but Quick Edit works for some things just fine.

[nicolebernd]

I wanted to provide some info.

I just experienced the same issue after using Elementor and trying to remove it in favor of a more lightweight option. When I disabled Elementor I got the error shown here. When I enabled it again it did not solve the problem. However, I can pinpoint the issue to the moment I deactivated Elementor.

I was trying to save a custom post type made with Metabox.io

I am using WordPress 5.3+ as well as the latest version of Elementor.

[stidch]

I don't know if the issue I face is exactly the same, but at least looks similar.

I cannot save any page, which contain a shortcode, which contain a call to a java-script method

For example:

onload="resizeIframe(this)"

In my case I try to resize an iframe with the advanced-iframe plugin. The full shortcode looks like this:

advanced_iframe src="https://xxx.com/script.php?parameter=value" frameborder="0" scrolling="no" onload="resizeIframe(this)"

In an html block above I'v defined the resizeIframe method.

<script>
function resizeIframe(iframe) {
  iframe.height = "10px" // required for reducing the size
  iframe.height = iframe.contentWindow.document.body.scrollHeight + "px";
}
</script>

If I remove the part

onload="resizeIframe(this)

from the shortcode I can successfully save the page. With I can't.

I've tried already with disabled plugins and default theme.

[stidch]

Just found out that my issue is most probably the one which is filed here: #48698