Google Visited. Your Server Said "No."
When Googlebot crawls your site and gets a 5xx error (500 Internal Server Error, 502 Bad Gateway, 503 Service Unavailable), it takes note.
Once? Google comes back later. No harm done.
Repeatedly? Google reduces its crawl rate. It starts to consider your site unreliable. Your pages may get temporarily deindexed. This directly impacts your crawl budget and crawl frequency.
The Threshold
There is no official threshold. But frequent 5xx errors over days or weeks will definitely impact your indexation and rankings. Google has confirmed this.
The Common Causes
Server overload during traffic spikes. Broken server configurations after updates. Database connection failures. Hosting provider issues. Bad deployments that crash the application.
The Fix
Monitor your uptime. Use Uptime Robot (free) or similar tools. Get alerts when your site goes down.
Check Google Search Console's Server Error report. If Google is encountering 5xx errors, you need to know about it — even if your own monitoring shows 99.9% uptime. Google might be hitting different pages or hitting during brief outages you missed. Your server response time (TTFB) is often the canary in the coal mine for server issues.
Fix the root cause. Upgrade hosting if needed. Add caching. Implement proper error handling.
Do not let server errors silently destroy your rankings. Track uptime as part of your 113-task SEO routine. Free. No credit card. 30 seconds.