Troubleshooting

Common router issues, debugging techniques, and solutions for troubleshooting Aurelia router problems.

This guide covers common router issues, debugging techniques, and solutions to help you quickly resolve routing problems in your Aurelia applications.

Common Issues and Solutions

1. Routes Not Matching

Problem: Configured routes are not being matched or components not loading.

Symptoms:

• Blank viewport

• No component loaded

• "Route not found" errors

Solutions:

Check Route Configuration

// ❌ Common mistake - Missing quotes around path
@route({
  routes: [
    { path: home, component: Home } // Missing quotes
  ]
})

// ✅ Correct
@route({
  routes: [
    { path: 'home', component: Home }
  ]
})

Verify Route Registration

// ✅ Ensure routes are properly registered
@route({
  routes: [
    { path: ['', 'home'], component: Home }, // Multiple paths
    { path: 'about', component: About }
  ]
})
export class App {}

// ✅ Or using static routes
export class App {
  static routes = [
    { path: 'home', component: Home }
  ];
}

Debug Route Matching

// Enable router debugging
import { ILogger, LogLevel } from '@aurelia/kernel';

// In main.ts
container.register(
  Registration.instance(ILogger, 
    new Logger().scopeTo('Router').setLevel(LogLevel.trace)
  )
);

2. Component Not Loading

Problem: Route matches but component doesn't appear.

Debugging Steps:

1. Check Viewport Configuration

<!-- ❌ Missing viewport -->
<nav>
  <a href="home">Home</a>
</nav>
<!-- No au-viewport! -->

<!-- ✅ Correct -->
<nav>
  <a href="home">Home</a>
</nav>
<au-viewport></au-viewport>

2. Verify Component Registration

// ✅ Register components if using string references
// main.ts
au.register(
  HomeComponent,
  AboutComponent
);

// ✅ Or use direct component references
@route({
  routes: [
    { path: 'home', component: HomeComponent } // Direct reference
  ]
})

3. Check Component Lifecycle

export class MyComponent implements IRouteViewModel {
  canLoad(params: Params): boolean | Promise<boolean> {
    console.log('canLoad called', params);
    return true; // Make sure this returns true
  }

  loading(params: Params): void | Promise<void> {
    console.log('loading called', params);
    // Check for errors here
  }
}

3. Navigation Not Working

Problem: Clicking links or calling router.load() doesn't navigate.

Common Causes and Fixes:

1. External Links Blocking Router

<!-- ❌ External attribute blocks router -->
<a href="internal-route" external>Link</a>

<!-- ✅ Remove external for internal links -->
<a href="internal-route">Link</a>

<!-- ✅ Use external only for external links -->
<a href="https://example.com" external>External Link</a>

2. Href vs Load Attribute Conflicts

<!-- ❌ Don't mix href and load -->
<a href="route1" load="route2">Conflicting</a>

<!-- ✅ Use one or the other -->
<a href="route1">With Href</a>
<a load="route2">With Load</a>

3. Router Configuration Issues

// ❌ Router not started
const router = container.get(IRouter);
// Missing: router.start(true);

// ✅ Proper router startup
RouterConfiguration.customize({
  // Your config
})

// Router starts automatically with AppTask

4. router.load('../1') throws UnknownRouteError

Symptom: await this.router.load('../1') rejects with UnknownRouteError: AUR3401 ... did you forget to add '..1' to the routes list of 'root'?, yet <a load="../1"> works.

Why it happens: router.load() always evaluates instructions in the root routing context unless you pass a context option, so ../ cannot be resolved relative to the current child router.

Fix: Resolve IRouteContext (or pass the component instance created by the router) and provide it in the navigation options.

import { resolve } from '@aurelia/kernel';
import { IRouter, IRouteContext } from '@aurelia/router';

export class StepNavigator {
  private readonly router = resolve(IRouter);
  private readonly routeContext = resolve(IRouteContext);

  async previousStep() {
    await this.router.load('../1', { context: this.routeContext });
  }

  async exitToParent() {
    await this.router.load('../../summary', {
      context: this.routeContext.parent ?? null,
    });
  }
}

If you need to navigate relative to different ancestors (for example inside a reusable widget), compute the target context at runtime (e.g., const parent = this.routeContext.parent ?? this.routeContext;) before calling router.load.

4. Parameters Not Available

Problem: Route parameters are undefined or not accessible.

Debugging:

1. Check Parameter Definition

// ❌ Incorrect parameter syntax
@route({
  routes: [
    { path: 'product/id', component: ProductComponent } // Missing :
  ]
})

// ✅ Correct parameter syntax
@route({
  routes: [
    { path: 'product/:id', component: ProductComponent }
  ]
})

2. Access Parameters Correctly

export class ProductComponent implements IRouteViewModel {
  private productId: string;

  canLoad(params: Params): boolean {
    console.log('All params:', params); // Debug output
    this.productId = params.id; // Access parameter
    return true;
  }

  // ✅ Alternative: Use ICurrentRoute
  attached() {
    const currentRoute = resolve(ICurrentRoute);
    const paramInfo = currentRoute.parameterInformation[0];
    console.log('Parameter info:', paramInfo?.params);
  }
}

5. Query Parameters Issues

Problem: Query parameters not working or not accessible.

Solutions:

1. Setting Query Parameters

// ✅ Recommended: let the router stringify query parameters for you
await this.router.load('search', {
  queryParams: {
    q: 'search term',
    page: '1'
  }
});

// ✅ Also supported: include query (and fragment) directly in the instruction string
await this.router.load('search?q=term#results');

2. Reading Query Parameters

export class SearchComponent {
  private currentRoute = resolve(ICurrentRoute);

  attached() {
    // ✅ Read from URLSearchParams
    const query = this.currentRoute.query;
    const searchTerm = query.get('q');
    const page = parseInt(query.get('page') || '1');

    console.log('Search term:', searchTerm);
    console.log('Page:', page);
  }
}

6. Hash Routing Issues

Problem: Hash routing not working correctly.

Configuration Check:

// ✅ Enable hash routing
RouterConfiguration.customize({
  useUrlFragmentHash: true
})

// ✅ Ensure base tag is correct for hash routing
// index.html
<base href="/">

7. Push State Routing Issues

Problem: Push state routing not working, especially on refresh.

Solutions:

1. Server Configuration

// ✅ Configure your server for SPA routing
// Example: Express.js
app.get('*', (req, res) => {
  res.sendFile(path.join(__dirname, 'index.html'));
});

2. Base Tag Configuration

<!-- ✅ Correct base tag -->
<base href="/">

<!-- ❌ Incorrect - empty base href breaks URL resolution -->
<base href="">

Debugging Techniques

1. Enable Router Logging

// main.ts - Enable detailed router logging
import { ILogger, LoggerConfiguration, LogLevel } from '@aurelia/kernel';

container.register(
  LoggerConfiguration.create({
    level: LogLevel.trace,
    colorOptions: 'colors'
  })
);

2. Router Event Monitoring

// Debug navigation with events
export class RouterDebugger {
  constructor() {
    const routerEvents = resolve(IRouterEvents);
    
    routerEvents.subscribe('au:router:navigation-start', (event) => {
      console.log('🚀 Navigation started:', event);
    });
    
    routerEvents.subscribe('au:router:navigation-end', (event) => {
      console.log('✅ Navigation completed:', event);
    });
    
    routerEvents.subscribe('au:router:navigation-error', (event) => {
      console.error('❌ Navigation failed:', event);
    });
    
    routerEvents.subscribe('au:router:navigation-cancel', (event) => {
      console.warn('⚠️ Navigation cancelled:', event);
    });
  }
}

3. Route State Inspection

// Inspect current router state
export class RouterInspector {
  private router = resolve(IRouter);
  private currentRoute = resolve(ICurrentRoute);

  inspectState() {
    console.log('=== Router State ===');
    console.log('Is navigating:', this.router.isNavigating);
    console.log('Current path:', this.currentRoute.path);
    console.log('Current URL:', this.currentRoute.url);
    console.log('Route tree:', this.router.routeTree);
    console.log('Parameter info:', this.currentRoute.parameterInformation);
    console.log('Query params:', Array.from(this.currentRoute.query.entries()));
  }
}

4. Component Lifecycle Debugging

export class DebugComponent implements IRouteViewModel {
  canLoad(params: Params, next: RouteNode, current: RouteNode | null): boolean {
    console.log('canLoad:', { params, next: next.path, current: current?.path });
    return true;
  }

  loading(params: Params, next: RouteNode, current: RouteNode | null): void {
    console.log('loading:', { params, next: next.path, current: current?.path });
  }

  canUnload(next: RouteNode | null, current: RouteNode): boolean {
    console.log('canUnload:', { next: next?.path, current: current.path });
    return true;
  }

  unloading(next: RouteNode | null, current: RouteNode): void {
    console.log('unloading:', { next: next?.path, current: current.path });
  }
}

Performance Issues

1. Slow Route Loading

Causes and Solutions:

1. Large Component Bundles

// ❌ Large synchronous imports
import { HugeComponent } from './huge-component';

@route({
  routes: [
    { path: 'huge', component: HugeComponent }
  ]
})

// ✅ Use dynamic imports for large components
@route({
  routes: [
    { path: 'huge', component: () => import('./huge-component') }
  ]
})

2. Heavy Lifecycle Operations

export class OptimizedComponent implements IRouteViewModel {
  // ❌ Heavy operations in canLoad
  async canLoad(params: Params): Promise<boolean> {
    await this.loadHeavyData(); // Blocks navigation
    return true;
  }

  // ✅ Move heavy operations to loading
  canLoad(params: Params): boolean {
    return true; // Quick validation only
  }

  async loading(params: Params): Promise<void> {
    // Heavy operations here don't block navigation decision
    await this.loadHeavyData();
  }
}

2. Memory Leaks

Common Causes:

1. Event Subscriptions Not Cleaned Up

export class ComponentWithSubscription {
  private subscription?: IDisposable;

  attached() {
    this.subscription = this.routerEvents.subscribe(
      'au:router:navigation-end',
      this.handleNavigation
    );
  }

  // ✅ Always clean up subscriptions
  detached() {
    this.subscription?.dispose();
  }
}

2. Large Route Trees

// ✅ Monitor route tree size
export class RouteTreeMonitor {
  inspectRouteTree() {
    const routeTree = this.router.routeTree;
    const nodeCount = this.countNodes(routeTree.root);
    
    if (nodeCount > 100) {
      console.warn('Large route tree detected:', nodeCount, 'nodes');
    }
  }

  private countNodes(node: RouteNode): number {
    return 1 + node.children.reduce((sum, child) => sum + this.countNodes(child), 0);
  }
}

Development vs Production Issues

1. Works in Development but Not Production

Common Causes:

1. Build Configuration

// ✅ Check dynamic imports are supported
// webpack.config.js
module.exports = {
  output: {
    chunkFilename: '[name].[chunkhash].js'
  }
};

2. Base Path Configuration

// ✅ Environment-specific base paths
const basePath = process.env.NODE_ENV === 'production' 
  ? '/my-app/' 
  : '/';

RouterConfiguration.customize({
  basePath
});

2. Different Behavior Between Hash and Push State

// ✅ Test both modes during development
// Use environment variable to switch
RouterConfiguration.customize({
  useUrlFragmentHash: process.env.USE_HASH_ROUTING === 'true'
});

Error Messages and Solutions

Common Error Messages

1. "No route found for path"

   • Check route configuration

   • Verify fallback routes

   • Enable route logging

2. "Component not found"

   • Verify component registration

   • Check import statements

   • Confirm component exports

3. "Navigation cancelled"

   • Check lifecycle hooks

   • Verify canLoad/canUnload return values

   • Look for thrown exceptions

4. "Viewport not found"

   • Ensure <au-viewport> is present

   • Check viewport names match

   • Verify viewport hierarchy

Quick Debugging Checklist

✅ Router Setup

• RouterConfiguration registered

• Router started with router.start(true)

• Base tag configured correctly

• Server configured for SPA (if using push state)

✅ Route Configuration

• Routes properly defined

• Paths have correct syntax

• Components imported/registered

• Fallback routes configured

✅ Navigation

• Viewports present in templates

• Links don't have conflicting attributes

• External links marked as external

• Navigation calls handle errors

✅ Components

• Lifecycle hooks return correct values

• Parameters accessed correctly

• Subscriptions cleaned up

• Error handling implemented

This troubleshooting guide provides practical solutions for the most common router issues, helping developers quickly identify and resolve routing problems.