# How to deal with token-related error codes? (/en/api-reference/faq/integration/token_related_issues)

> For AI agents: see the complete documentation index at [llms.txt](/llms.txt).

When a primary/secondary certificate is enabled for your project, you use dynamic tokens to authenticate users. This page lists token-related error codes and event callbacks you may receive, provides triggering causes and solutions, and helps you troubleshoot.

## 101: App Id invalid [#101-app-id-invalid]

**Problem**

The SDK for native platforms returns the `ERR_INVALID_APP_ID` (101) error code when initializing the Agora service. Alternatively, the SDK calls back the `onError` event and returns the `ERR_INVALID_APP_ID` (101) error code when calling `joinChannel`.

**Cause**

An invalid App Id usually caused by the incorrect data type.

**Solution**

Check that the App Id data type is string and reinitialize the service.

## 109: Token expired [#109-token-expired]

**Problem**

The SDK for native platforms triggers the `onError` event and returns the `ERR_TOKEN_EXPIRED` (109) error code when calling `joinChannel`.

**Cause**

The token has expired.

**Solution**

If the token has expired, generate a new token on the server and call `renewToken` to rejoin the channel.

## 110: Token invalid [#110-token-invalid]

**Problem**

The SDK for native platforms triggers the `onError` event and returns the `ERR_INVALID_TOKEN` (110) error code when calling `joinChannel`.

**Cause**

The generated token is invalid. This may happen for one of the following reasons:

* Primary/secondary certificate **is enabled** in your project, but the token is **not passed** when joining the channel. Alternatively, primary/secondary certificate **is not** enabled, but the token **is passed** to join the channel.

* The App Id, user ID, and channel name you used when generating the token on the server do not match the values you filled in when initializing and joining the channel.

**Solution**

Before joining the channel, check whether the project corresponding to the App Id you filled in during initialization has a primary/secondary certificate enabled.

* If primary/secondary certificate is not enabled, you cannot use a token to join the channel.
* If primary/secondary certificate is enabled in the project and App Id-only joining is allowed, you can join the channel using only the App Id or using the token generated by the primary/secondary certificate to join the channel.
* If primary/secondary certificate is enabled in your project and App Id-only joining is not allowed, you must use a token to join the channel.

When confirming the use of a token to join the channel, also confirm the following:

* The App Id used to generate the token is consistent with the App Id filled in when initializing the token server.
* The user ID used to generate the token is consistent with the user ID filled in when joining the channel, and the data type is also consistent.
* The channel name used to generate the token is consistent with the channel name filled in when joining the channel.

## Token expiration event callback [#token-expiration-event-callback]

To improve the communication experience, Agora provides the following two callbacks to inform the client that their token is about to expire or has expired:

* `onTokenPrivilegeWillExpire`: This callback indicates that the token will expire within 30 seconds. When you receive this callback, generate a new token on the server side and call `renewToken` to pass the newly generated token to the SDK.
* `onRequestToken`: This callback indicates that the token has expired. When you receive this callback, generate a new token on the server side and call `joinChannel` to rejoin the channel.

## Error code comparison [#error-code-comparison]

The table below provides the error code equivalents for different languages.

| Error code | Java/C++/C#          | Objective-C                  |
| ---------- | -------------------- | ---------------------------- |
| 101        | `ERR_INVALID_APP_ID` | `AgoraErrorCodeInvalidAppId` |
| 109        | `ERR_TOKEN_EXPIRED`  | `AgoraErrorCodeTokenExpired` |
| 110        | `ERR_INVALID_TOKEN`  | `AgoraErrorCodeInvalidToken` |