Code 509

HTTP 509 (Bandwidth Limit Exceeded) is an unofficial status code used by some web hosting providers to indicate that the site has exceeded its allocated monthly bandwidth quota. When this code is returned, the server stops serving the website until the billing period resets or the hosting plan is upgraded.

HTTP 509 errors are typically identified through hosting provider dashboards and server log analysis. From an SEO perspective, bandwidth exhaustion events are treated similarly to 503 errors by Googlebot — extended downtime may be noted in Google Search Console's Coverage report as crawl anomalies.