How to trace an Error when it says nothing about any plugin?

To help debug, consider what was the most recent change to the website right before you noticed this error. Were there any new plugins installed, was WordPress upgraded, anything updated, modified or deleted in the theme and plugins?

Normally it is recommended to make a clone of the site and test with that (or if you want to make a change with the live site… make a back-up first) Then disable one plugin at a time and see if the error goes away. That will help pinpoint the trouble maker.

** Very important, before debugging any error on a site, if you have any caching plugins, then disable it first. Cached pages can really throw you off.

Also, if you have SEO plugins, I suggest disabling those next. They usually interfere with the WordPress themes and normally could create trouble.