Glossary · Monitoring

Planned Downtime

Planned downtime is a scheduled period when a service is intentionally unavailable or degraded for maintenance, upgrades or migrations.

Updated October 28, 2026

Planned downtime is time when a service is deliberately taken offline or limited, at a moment chosen in advance, to do work that cannot safely happen while traffic flows. Typical causes are database schema changes, OS upgrades, hardware swaps and migrations.

Why it matters

Planned and unplanned downtime hurt differently. Users can adapt to an announced window, but a surprise outage costs trust. Contracts often exclude planned downtime from SLA calculations, so the definition, notice period and maximum length matter. Search engines also treat a short, honest outage better when the server answers correctly.

Example

During a database upgrade, serve a maintenance page with the right signal so crawlers and monitors know it is temporary:

HTTP/1.1 503 Service Unavailable
Retry-After: 3600
Content-Type: text/html

Meanwhile, pause alerts or schedule a maintenance window in your monitor so the work does not page anyone or count against reported uptime.

Common mistakes

  • Returning 200 OK on the maintenance page, which can get "Down for maintenance" indexed.
  • Forgetting to end the window in your monitoring, so a real failure afterward goes unreported.
  • Announcing too late. Post on your status page ahead of time and again when work starts and ends.

Get notified when this term updates

Plus occasional practical tips on uptime and monitoring, nothing else. Unsubscribe anytime.

Keep reading

Glossary · MonitoringMaintenance WindowA maintenance window is a pre-announced period set aside for changes such as upgrades or migrations, during which brief downtime is expected.Guide · MonitoringStatus Page Message Templates: Incident and Maintenance ExamplesCopy-ready status page messages for investigating, identified, monitoring and resolved updates and planned maintenance, with tone rules and worked examples.8 min readGuide · Downtime & Errors503 Service Unavailable: What It Means and How to Fix It Step by StepDiagnose a 503 Service Unavailable error from overload, maintenance mode, exhausted workers or a dead backend, with fixes for WordPress, nginx, Apache and IIS.8 min readError fix · Server errorsHTTP 503 Retry-After and Maintenance Pages: Doing It RightServe a proper 503 Service Unavailable with a Retry-After header for maintenance windows, with nginx, Apache and CDN examples and notes on SEO and caching.4 min readGlossary · MonitoringAlert (Monitoring)A monitoring alert is an automatic notification sent when a check or metric crosses a defined condition, such as a site failing to respond.Glossary · MonitoringAlert DeduplicationAlert deduplication merges repeated alerts about the same underlying problem into one incident, so responders are notified once rather than hundreds of times.

This page is general information written by our editorial team and updated when documentation changes. Servers and providers differ, so test changes safely first. See our editorial policy and disclaimer.