Recently installing the Jetpack Plugin on a website for its many benefits, and trying to enable any of the site fucntions brought up an error
Error updating settings. Api404Error
This plugin actually relies on WordPress JSON Query which can be found in the ‘dir’ /wp-json/ e.g. http://www.pariswells.com/blog/wp-json/
For the effected website this was not found ( 404) , this website was actually copied from another site so the .htaccess was mis copied.
Recreatiing the Permalinks for the site found under Settings ( Just set to something else and save , then change it back recreates this )
This resolved the issue
Trackback from your site.