| name | angular-errors |
| description | Troubleshooting guide for Angular runtime and compiler errors with per-code reference docs. |
| license | MIT |
| metadata | {"author":"Copyright 2026 Google LLC","version":"1.0"} |
Angular Error Troubleshooting Guide
Use this skill when Angular reports an NGxxxx error code and you need fast root-cause and fix guidance.
Recommended Workflow
- Identify the exact error code (
NG0100, NG8002, etc.) from terminal or browser console.
- Determine whether it is a runtime or compiler error.
- Open the corresponding file in
references/ (for example references/NG0201.md).
- Apply fixes from the sections:
Why this error happens, How to debug, and How to fix.
- Re-run your app/tests and verify the error is resolved.
Runtime Errors
Runtime errors occur while your application is running. This section summarizes common Angular runtime errors.
| Code | Name |
|---|
| NG0100 | Expression Changed After Checked |
| NG01101 | Wrong Async Validator Return Type |
| NG01203 | Missing value accessor |
| NG0200 | Circular Dependency in DI |
| NG0201 | No Provider Found |
| NG0203 | inject() must be called from an injection context |
| NG0204 | Invalid Injection Token |
| NG0205 | Injector has already been destroyed |
| NG0207 | EnvironmentProviders in wrong context |
| NG0209 | Invalid multi provider |
| NG02200 | Missing Iterable Differ |
| NG02800 | JSONP support in HttpClient configuration |
| NG02802 | Headers not transferred by HttpTransferCache |
| NG0300 | Selector Collision |
| NG0301 | Export Not Found |
| NG0302 | Pipe Not Found |
| NG0401 | Missing Platform |
| NG0403 | Bootstrapped NgModule does not specify a root component |
| NG0500 | Hydration Node Mismatch |
| NG05000 | Hydration with unsupported Zone.js instance |
| NG0501 | Hydration Missing Siblings |
| NG0502 | Hydration Missing Node |
| NG0503 | Hydration Unsupported Projection of DOM Nodes |
| NG0504 | ngSkipHydration flag is applied to an invalid node |
| NG0505 | No hydration info in server response |
| NG0506 | Application remains unstable |
| NG0507 | HTML content was altered after server-side rendering |
| NG0602 | Disallowed function call inside reactive context |
| NG0750 | @defer dependencies failed to load |
| NG0751 | @defer behavior when HMR is enabled |
| NG0910 | Unsafe bindings on an iframe element |
| NG0912 | Component ID generation collision |
| NG0913 | Runtime Performance Warnings |
| NG0919 | Circular Dependency Detected |
| NG0950 | Required input is accessed before a value is set |
| NG0951 | Child query result is required but no value is available |
| NG0955 | Track expression resulted in duplicated keys for a collection |
| NG0956 | Tracking expression caused re-creation of DOM structure |
Compiler Errors
Compiler errors occur when the Angular compiler fails to process your code, usually due to syntax or structural issues. This section summarizes common Angular compiler errors.
| Code | Name |
|---|
| NG1001 | Argument Not Literal |
| NG2003 | Missing Token |
| NG2009 | Invalid Shadow DOM selector |
| NG3003 | Import Cycle Detected |
| NG6100 | NgModule.id set to module.id anti-pattern |
| NG8001 | Invalid Element |
| NG8002 | Invalid Attribute |
| NG8003 | Missing Reference Target |
Detailed per-code guidance is available in references/NGxxxx.md files.
If you need additional framework context, use the official Angular Errors guide.
