PyPI Partial Outage

This incident has been resolved.

We have not seen a return of the traffic that caused this incident after removing the temporary block. We will open a new incident if we need to take action again.

We have removed the temporary block and are continuing to monitor.

Our block is in place and systems are stable, but we are not satisfied with having to block such a generic user-agent. If you are aware of a system that began a mass crawl of PyPI's JSON release endpoints starting at around 22:05 UTC 2025-05-25, please contact admin@pypi.org.

We have identified a flood of requests from a cluster using the `python-requests/2.32.3` User-Agent, and attempting to hit all JSON project/releasese en masse. This causes excessive cache misses, which are overwhelming our backends. A temporary block has been put in place.

We have identified a large increase in CDN cache misses causing excess load on our backends. We are working to determine the reason for this increase.

We are working to investigate a partial outage in the PyPI backends.