> ## Documentation Index
> Fetch the complete documentation index at: https://www.cometchat.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Error Codes

> Error Codes for CometChat REST API.

Error codes specific to the Calls APIs.

## Calling Errors

| Error Code                      | Description                                                                            |
| ------------------------------- | -------------------------------------------------------------------------------------- |
| `ERR_CALLING_SELF`              | User is initiating a call with themselves.                                             |
| `ERR_CALL_BUSY_SELF`            | The initiator is already on another ongoing call.                                      |
| `ERR_CALL_BUSY_GROUP`           | The group already has an ongoing call.                                                 |
| `ERR_CALL_BUSY_USER`            | The recipient is already busy on another call.                                         |
| `ERR_EMPTY_CALL_SESSION_ID`     | The session ID is empty.                                                               |
| `ERR_CALL_SESSION_NOT_FOUND`    | The call does not exist.                                                               |
| `ERR_CALL_TERMINATED`           | The call has ended. Cannot update the status of a terminated call.                     |
| `ERR_CALL_GROUP_ALREADY_JOINED` | The user is already a member of the group call.                                        |
| `ERR_CALL_GROUP_ALREADY_LEFT`   | The user has already left the group call.                                              |
| `ERR_CALL_INVALID_INIT`         | Call status cannot be updated to `initiated`.                                          |
| `ERR_CALL_USER_ALREADY_JOINED`  | The one-to-one call was already joined by the recipient.                               |
| `ERR_CALL_GROUP_INVALID_STATUS` | Invalid call status for a group call (e.g., group calls cannot have a busy status).    |
| `ERR_CALL_ONGOING_TO_INVALID`   | Invalid status transition for an ongoing call (e.g., ongoing call cannot become busy). |
| `ERR_CALL_NOT_A_PART`           | The user is not part of the call.                                                      |
| `ERR_CALL_EMPTY_JOINED_AT`      | The `joinedAt` body parameter is required to join a group call.                        |
| `ERR_CALL_NOT_STARTED`          | Call status cannot change from initiated to ended directly.                            |

## Authentication Errors

| Error Code                  | Description                                      |
| --------------------------- | ------------------------------------------------ |
| `AUTH_ERR_EMPTY_APIKEY`     | The `apikey` header is missing from the request. |
| `AUTH_ERR_APIKEY_NOT_FOUND` | The provided API key is invalid.                 |
| `AUTH_ERR_NO_ACCESS`        | The API key doesn't have the required scope.     |