How to Fix “The response is not a valid JSON response” Error in WordPress

I faced this issue once I get the HTTPS for my domain. Recently I added an SSL certificate to my site using the free version of Cloudflare. After that, I was not able to add new pages or add new posts to my Word Press site. When I was trying I got an error like “The response is not a valid JSON response”. The reason behind this is “Mixed content error due to the use of SSL certificate”.

I can suspect that happens because of your SSL (Security Socket Layer) on your WP website (HTTPS). It may happen some of content deliver through a secure manner (HTTPS) and other content deliver non security HTTP protocol.

This happens when both contents (HTTPS & HTTP) transmit the same time to your web browser. avoid that I used a plugin called “Really Simple SSL “.,
more than 40 million users are using this plugin.

To fix the issue, go to Settings > SSL. This will open the plugin’s settings. Now click on the Settings tab.

Now you have to make sure below options are turn on if not please turn on.

1. Mixed content fixer – It is preventing the mixed content issue.
2. Use an alternative method to fix mixed content – This will ensure that “the response is not a valid JSON response”

After saving, you won’t be able to see an error like “the response is not a valid JSON response”. You can create new posts and pages once you follow the instructions correctly.