Error “Failure to update. The response is not a valid JSON.” in WordPress. How to fix?

Clock on the wall illustrating missed schedule error in WordPress

Did you prepare a change in content on WordPress, and received the error “Failure to update. The response is not a valid JSON.” preventing the update of your text? Understand how to fix this problem.

The first step is to start by understanding the reason, and the answer to its cause is: it depends. There are several reasons why this error may appear in WordPress, but it could be directly related to your hosting server, your site’s security service, .htaccess file, incompatibility with some plugin or theme.

Try using the following methods to find what works for you.

Activate the Classic Editor

The first reason that might be the cause of most problems involving the JSON error is the text editor, and switching to the Classic Editor solves the situation most of the time. To use the Classic Editor, you will need to install and activate the Classic Editor plugin on your WordPress site.

Suggested reading: How to install a plugin in WordPress

Please keep in mind that if your site uses the modern block editor, it will be replaced by the old classic editor and this change will impact the way your texts are edited in WordPress, as well as the formatting and layout edited with the block editor. Safeguard your site by having a copy of the files, if necessary.

After installing and activating the new plugin, go back to the page where the error occurred and try to update it with the desired change. If the problem still persists, move on to step two.

Check the .htaccess file

If there is any inconsistency with the rules for some reason, your CMS will not update the page.

To fix this, go to Settings > Permalinks in your administrative panel. It’s likely that you haven’t accessed this section for some time in your WordPress installation, and keeping its impacts in mind, we won’t do anything permanent here.

Change the configuration of the permalinks to another one, update, test the text updates and return to what was saved before.

Still not able to get rid of it? Move on to the next topic.

Check your installed theme or plugin

Now we will try to find out if your theme or plugin is causing the problem.

To do this, go to Appearance, Themes in your WordPress panel. Then, activate the most recent default WordPress theme (at the time I am writing this article, it’s Twenty Twenty-Two) and check if it was resolved. Otherwise, return to your original theme.

The error can also be caused by a plugin and in that case, you can disable all plugins on your site and check again. Try to remember if any plugin was recently installed or updated and start by deactivating it. If you can make the update after that, you will know that this plugin is causing the problem.

Set up an SSL certificate

Having a security certificate is important to ensure that your users have access to the pages of your site, and for this reason, ensuring that your site uses an SSL certificate is important to correct the message “Failure to update. The response is not a valid JSON”.

You can verify if your site is using the SSL certificate by observing your site’s URL. After your site is loaded in a web browser, click on the upper search bar and make sure your URL starts with HTTPS.

If it does not appear and changing the address in the bar from HTTP to HTTPS does not work, then probably an SSL certificate has not been issued for your site.

The validity of SSL certificates expires after a certain period, so you can also check if your SSL certificate is still valid. If it is invalid, seek to renew the SSL certificate to correct SSL-related issues with your hosting provider.

Recommended reading: “Linking to HTTP pages does not affect SEO. But is it a good practice?” Written to the Rock Content blog.

Did any of the solutions put an end to the problem? Tell me what you think in the comments of this post!

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