India, Nov. 10 -- YouTube appeared to be experiencing major problems for many users on Wednesday, but the platform itself wasn't actually down. Instead, the issue was triggered by ad blockers, a recurring flashpoint in YouTube's ongoing crackdown on third-party tools that interfere with ads. What looked like a widespread outage turned out to be a problem affecting only those using browsers with ad-blocking extensions enabled.

Reports on DownDetector spiked early in the day, with thousands of users saying that YouTube was refusing to load properly. Some were met with empty homepages, missing thumbnails, or pages that wouldn't scroll. Many assumed it was a server outage. But a pattern quickly emerged: switching to a browser without an ad b...