It is never the plugin everyone blames

Every emergency arrives with a theory attached. Someone updated a plugin, the site went down, therefore the plugin. It is a tidy story and it is usually wrong.

What actually happened, most of the time: the update was the first thing in months to ask the database for something expensive, and the server had been one query away from falling over since long before anyone touched it. Roll the plugin back and the site comes up. Nothing is fixed.

So I stopped trusting the last change and started reading the logs from before it. The question is not what broke. It is what was already fragile enough to break.