> For the complete documentation index, see [llms.txt](https://backbench.gitbook.io/backbench-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://backbench.gitbook.io/backbench-docs/troubleshooting-and-support/error-codes.md).

# Error Codes

Backbench has following error codes, this can be used to debug your application on backbench.

| Code | Reason              | Description                                                                                                                                        |
| ---- | ------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------- |
| 400  | Malformed Request   | Since we have support of nodejs 5.10.1, any code above this can cause this error.                                                                  |
| 503  | Service Unavailable | Due to following reasons:-                                                                                                                         |
|      |                     | **Callback parameter's missing**, because it's a required parameter.                                                                               |
|      |                     | **Runtime Failure**, due to sterr of the program. Similar to crash in express framework.                                                           |
|      |                     | **Build Failure in App**: It occurs while partial build, while saving your app when connection is slow, in this case you just have to hit refresh. |
| 504  | Timed out           | Happens when your program is running more than the given timeout duration. In this case make sure your program terminates within timeout.          |