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429 Too Many Requests error⚓︎

Why am I seeing this error?⚓︎

If you are observing 429 errors when downloading from Maven Central, the likely cause is that you are being rate limited for overloading the service. Although further information is provided in the body of the response, some build tools may not expose that information. As such, we are documenting it here for easier visibility.

In order to keep Maven Central operating as a free service to all of our users, we need to protect ourselves from usage that drastically increases our operating costs. For more information on this decision, please refer to this blog article.

What can I do to resolve the error?⚓︎

If you are downloading from Maven Central at a significantly high rate, we would suggest that you look into a caching proxy or contact the email address in the linked blog article to work out an arrangement.

If you are not excessively downloading from Central, it is likely that your traffic is being grouped together with a larger pool of users, for a variety of reasons. This could be due to your traffic coming from a single organization or could be due to how your cloud hosting provider handles outgoing traffic to Central. If you suspect that is the case, please reach out to them and have them work with us directly.

If you are experiencing timeouts for your requests or other HTTP response codes, it is unrelated to the rate limits described above. We chose a quick 429 response over throttling responses and other potential approaches because we felt that it would be the most effective way to clearly communicate with users who were consuming an excessive amount of bandwidth.

In the case of those errors, there may be a momentary issue with our CDN provider. We would suggest that you wait a short amount of time and retry your build. If it fails consistently, please reach out and contact Central Support in order for us to investigate further.