The problem affected internet pages across the whole planet, and lasted for around 40 minutes before engineeers were able to fix it.
"We periodically receive updates to that list and received one such update to release on the site this morning. Unfortunately (and here's the human error), the URL of '/' was mistakenly checked in as a value to the file and '/' expands to all URLs. Fortunately, our on-call site reliability team found the problem quickly and reverted the file," Google said in its official blog.
