Cloudflare goes down again amid massive outages affecting various websites and apps, even DownDetector crashes

As of 5:59 PM on December 5, 2025, many websites and apps are experiencing connectivity issues. Cloudflare reports the issue.

The result of accessing pixiv is shown below. A 500 error occurs, indicating that the problem is on the server side.

Cloudflare's official website also gives a 500 error.

DownDetector, which compiles the status of various websites, is also down.

By the way, DownDetector's Down Detector , which monitors whether DownDetector is up or down, shows 'OK'. It doesn't seem to be working properly.

・Added on December 5, 2025 at 6:15 PM
Cloudflare fixed the issue at 18:12 on December 5, 2025, Japan time. Various websites are now accessible again.

・Added on December 6, 2025 at 7:59 PM
Cloudflare published a blog post explaining the outage. The impact lasted for 25 minutes, from 5:47 PM to 6:12 PM Japan time on December 5, 2025, and was caused by changes to address vulnerabilities. Following the large-scale outage on November 18, 2025, Cloudflare was implementing changes to prevent a single outage from affecting the entire system. However, the changes were not yet fully implemented, and the current outage could not have been prevented.

Cloudflare outage on December 5, 2025
https://blog.cloudflare.com/5-december-2025-outage/