As @LTUser already stated, it could be a faulty plugin. In my situation it was caused by a bug in wp-config.php, site worked fine, but WP toolkit crashed on the Warning.
Finding the cause
I found that bug by editing...
Same here, lots of clients are complaining about these messages.
Failed to reset cache for the instance #218: Failed to parse wp-config.php: Uncaught TypeError: Argument 1 passed to WP_CLI\Runner::WP_CLI\{closure}() must be an instance of Exception, instance of Error given in...
Lots of obvious spam messages get through. But when I check the same message (spamassassin -d -t < path.to.file) the score is way higher then what the headers show me. Any suggestions on how to fix this?
Mail headers are showing this:
X-Spam-Level: ****
X-Spam-Status: No, score=4.4 required=5.0...