I use WPS Hide Login maybe is the problem ?
Now I can’t login perfect subscribers are filling up our support email queue
I get the same error, I went to troubleshooting mode and found after activiting all plugins but yours , or disabling all plugins and only activating yours this happens “Updating failed. The response is not a valid JSON response.”
but you have another plugin that opens external links and that one works fine without the error.
Hope this helps someone else https://wordpress.org/plugins/open-external-links-in-a-new-window/
