Single-SPA Error Handling

Error Handling Overview

Error Handling is a building block you will reach for often in single-spa. It keeps related logic together and makes your intent obvious to reviewers and future maintainers.

When you learn error handling properly, you avoid the guesswork that leads to bugs and rework. The example below shows the shape you will use in most real single-spa projects.

import { registerApplication, start } from 'single-spa';

registerApplication({
  name: '@org/app',
  app: () => System.import('@org/app'),
  activeWhen: ['/app'],
});

start();

single-spa orchestrates multiple framework apps on one page through a root config.

Error Handling Example

registerApplication({
  name: '@org/app',
  app: () => System.import('@org/app'),
  activeWhen: ['/app'],
});
start();

• Start from a minimal Error Handling example and grow it only as needed.
• Keep configuration explicit so Error Handling behaves the same in every environment.
• Name things clearly so teammates understand your Error Handling at a glance.
• Add tests around Error Handling early to lock in expected behaviour.

Single-SPA Cheatsheet

Core single-spa APIs related to error handling.

How Error Handling Works in Single-SPA

Error Handling is part of how single-spa lets multiple applications — even in different frameworks — coexist on one page. A root config registers each app and controls when it is active.

single-spa orchestrates multiple framework apps on one page through a root config.

• A root config registers apps and calls start().
• Each app exports bootstrap, mount, and unmount lifecycles.
• activeWhen decides which routes each app owns.
• Import maps resolve each app's bundle at runtime.

Practical Guidance for Error Handling

For reliable micro frontends, error handling should isolate failures and keep shared state minimal. Let each team own its app end to end while agreeing on a few shared contracts.

Common Mistakes

• Copying error handling snippets without understanding what each line does.
• Skipping error handling and edge cases when wiring up error handling.
• Leaving error handling untested, so regressions slip into production.
• Over-engineering error handling before you actually need the extra flexibility.

Key Takeaways

• Error Handling is a core part of working effectively with single-spa.
• Start small and keep error handling focused on a single responsibility.
• Apply consistent patterns so error handling scales across your project.
• Test and document error handling to keep it maintainable over time.