Just today I was publishing a new WordPress blogpost – it was a quite basic blog post with only text and some images – when I suddenly received the following error message when I clicked on Publish:
Publishing failed. The response is not a valid JSON response

I remember having seen the very same error earlier when uploading images to WordPress, but I couldn’t remember how I solved the issue at the time.
Here are some possible steps for you to take in order to solve the WordPress error message.
First, simply try again
The very first ting may sound silly, but I’ve had success with this method before. For some reason, the action fails and trying again a second time is solving the issue. Strange but successful – so worth trying (even 3 times) and you may be lucky 🍀