Deploy, Regression & Silent Failure Guides

Guides to the failures that ship with a release: layouts that shift, pages that go blank, scripts and APIs that fail in the browser, redirects that loop. What causes them, and how to catch them within minutes of a deploy.

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Most production incidents on websites are not outages. They are regressions: something that worked yesterday stopped working after a deploy, a plugin update, or a change on a third-party service. The server stays healthy, so they go unnoticed until someone complains.

Start with the ways a website breaks after a deploy for the big picture, then use the post-deploy and launch checklists as runbooks. The deeper guides cover specific failure types when you are debugging one.

Suggested reading path

Pick the step that matches where you are.

1

Know what to look for

Read the ways a website breaks after a deploy and why websites break without going offline.

2

Build a post-deploy routine

Use the post-deploy monitoring guide and the pre-launch checklist as repeatable runbooks.

3

Automate it in the pipeline

The CI/CD guide covers triggering checks after each release instead of waiting for the next schedule.

4

Debug a specific failure

Blank pages, JavaScript errors, API failures, third-party scripts, and redirects each have their own guide.

All guides in this topic

Ordered from the most common problems to deeper reference material.

Article

5 Ways a Website Breaks After a Deploy

Published

Why a website breaks after deploy without going down: the 5 most common post-deploy failures uptime monitors miss, and how to catch them before your users do.

Read 5 Ways a Website Breaks After a Deploy

Article

Post-Deploy Monitoring: What to Check After Every Deploy

Published Updated

Deploys are the riskiest moment for your website. Learn how deployment monitoring catches post-deploy regressions within minutes, before users find them.

Read Post-Deploy Monitoring: What to Check After Every Deploy

Article

Website Monitoring Checklist: 41 Checks

Published Updated

Use this 41-point website monitoring checklist to cover uptime, SSL, DNS, forms, checkout, journeys, alerts, launch checks, and incident response.

Read Website Monitoring Checklist: 41 Checks

Article

robots.txt Monitoring

Published

A one-off robots.txt test only describes today. Here is what breaks robots.txt in production, how Google reacts to each failure, and how to monitor the file.

Read robots.txt Monitoring

Article

CI/CD Website Monitoring

Published

How to fit website monitoring into CI/CD: verify each deploy in production, catch regressions the moment they ship, and build a post-deploy safety net.

Read CI/CD Website Monitoring

Article

What Is Visual Regression Testing?

Published Updated

Visual regression testing catches layout and UI changes that break how your site looks. Here's how it works and why it matters for non-technical website owners.

Read What Is Visual Regression Testing?

Article

Why Websites Break Without Going Offline

Published Updated

Learn why websites can break without going fully offline and how website health monitoring helps detect silent failures.

Read Why Websites Break Without Going Offline

Article

What Causes Blank Pages on Websites?

Published Updated

Eight causes of blank pages on websites, the status code each one returns, how to confirm it, and why five of the eight never trigger an uptime alert.

Read What Causes Blank Pages on Websites?

Article

How to Monitor JavaScript Errors on a Website

Published Updated

Two ways to monitor JavaScript errors: an SDK that reports what real visitors hit, and a scheduled browser check that finds them without touching the site.

Read How to Monitor JavaScript Errors on a Website

Article

How to Monitor Third-Party Scripts on Your Website

Published

Learn how to monitor third-party scripts on your website so a broken tag, chat widget, or payment script gets caught before it breaks pages for visitors.

Read How to Monitor Third-Party Scripts on Your Website

Article

How to Monitor API Failures That Break Web Pages

Published Updated

Learn how to monitor API failures that break web pages, including failed XHR and Fetch calls, missing data, slow dependencies, and broken customer actions.

Read How to Monitor API Failures That Break Web Pages

Article

API Monitoring: The Endpoints Your Website Depends On

Published

API monitoring for websites: third-party API failures silently break pages. Learn how to monitor the endpoints your site depends on and catch failures first.

Read API Monitoring: The Endpoints Your Website Depends On

Article

How to Monitor Website Redirects

Published

A redirect can send your visitors to a page you do not control while uptime stays green. Learn how to monitor website redirects and catch off-site landings.

Read How to Monitor Website Redirects

Related NorthDuty pages

Product pages, tools, and comparisons connected to this topic.

Feature

Deployment Monitoring

Automatically run health checks and user journeys the moment your site is deployed or your CMS publishes a change.

Explore Deployment Monitoring

Feature

JavaScript Error Monitoring

Monitor JavaScript errors and exceptions from a real browser on a schedule — no SDK on your site. See which page broke, when, and what the browser reported.

Explore JavaScript Error Monitoring

Tool

robots.txt Tester

Free robots.txt checker and tester. Validate any site's robots.txt, see every rule and sitemap line, and test whether a URL is blocked for Googlebot.

Open robots.txt Tester

Frequently Asked Questions

Answers to common questions about NorthDuty and website monitoring.

What should I check right after a website deploy?

The homepage and top landing pages render correctly, key journeys like checkout, signup, and forms complete, there are no new JavaScript errors or failed API calls, redirects resolve, and robots.txt did not change. A journey run straight after the deploy shows the failed step with a screenshot if something broke.

How is visual regression testing different from post-deploy monitoring?

Visual regression testing compares screenshots in a test environment before release. Post-deploy monitoring checks the live site on a schedule and after deploys, running health checks and journeys, which also catches breakage caused by content edits, plugins, and third-party scripts.

Start monitoring your website with NorthDuty today.

Trigger NorthDuty after every deploy to re-run health checks and journeys, so regressions surface in minutes instead of support tickets.

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