503 Service Unavailable
503 means the server is temporarily unavailable. It’s OK for short maintenance windows, but long-term 503s hurt crawling and indexing.
Definition
503 Service Unavailable is a temporary server error status code often used during maintenance or overload. For SEO, short-lived 503s typically don’t immediately drop indexed pages, but prolonged 503s reduce crawl frequency and can lead to deindexing.
Why it matters
- Correct status codes during maintenance reduce indexing risk
- Long-lived 503s can lead to visibility loss
- Retry-After can guide crawlers on when to return
How to implement
- Use 503 (optionally with Retry-After) for short maintenance
- Keep the maintenance window short and monitor crawl behavior
- After recovery, ensure key pages return 200 and resubmit sitemaps if needed
Related
Tutorials
Tools
FAQ
Common questions about this term.