JSON error wordpress

try_files $uri $uri/ /index.php?q=$uri&$args;

add in nginx conf location part

Was troubled with this error. It was also a nuisance having the index.php in the middle of the url. I tried all the published fixes without success, including the Cloudflare plugin. In the end, the fix was in the apache2.conf – changed AllowOveride to All for / and /var/www and restarted Apache. Then set permalinks to /%postname%/ and it all worked.

Error message: The response is not a valid JSON response.” is overwhelmingly seen in the new Block editor called Gutenberg. The easiest way to resolve the updating error is by disabling Gutenberg and switching back to the Classic editor. As they say, old is Gold. You can install the Classic Editor plugin for this.

if getting error on widgets saving then Classic Widgets add this plugin