# Alert Troubleshooting Guide

This page provides troubleshooting guidance for EMQX Cloud alerts. Use it to review an alert's trigger conditions, identify likely causes, and take the recommended corrective actions.

## Serverless Deployments

### Resources and Quotas

| Alert | Description |
| :--- | :--- |
| [Session Limit Reached](./session_limit_reached.md) | Triggered when the number of client connections reaches the deployment limit. |
| [Serverless TPS Limit Reached](./sls_tps_limit_reached.md) | Triggered when the deployment reaches its transactions per second (TPS) limit. |
| [Free Traffic Quota Exhausted](./free_traffic_limit_reached.md) | Triggered when the deployment's free traffic usage reaches a specified threshold. |
| [Free Connection Minutes Limit Reached](./free_minutes_limit_reached.md) | Triggered when the deployment's free connection minutes reach a specified threshold. |
| [Free Rule Actions Limit Reached](./free_actions_limit_reached.md) | Triggered when the deployment's free rule action executions reach a specified threshold. |

### Data Integration

| Alert | Description |
| :--- | :--- |
| [Connector Status Abnormal](./connector_abnormal.md) | Triggered when a data integration connector enters an abnormal state. |
| [Action Status Abnormal](./action_abnormal.md) | Triggered when a data integration action enters an abnormal state. |

## Dedicated Deployments

### Authentication and Access Control

| Alert | Description |
| :--- | :--- |
| [High Volume of Authentication Failures](./authn_failures.md) | Triggered when a large number of client authentication attempts fail. |
| [High Volume of ACL Denials](./authz_failures.md) | Triggered when a large number of client authorization (ACL) checks fail. |
| [External Auth/ACL Module Status Abnormal](./authn_authz_abnormal.md) | Triggered when an external EMQX authentication or authorization (ACL) module enters an abnormal state. |
| [Client Banned for Connection Flapping](./flapping_detected.md) | Triggered when a client is temporarily banned after repeated connection flapping. |

### Resources and Quotas

| Alert | Description |
| :--- | :--- |
| [Session Limit Reached](./session_limit_reached.md) | Triggered when the number of client connections reaches the deployment limit. |
| [TPS Limit Reached](./tps_limit_reached.md) | Triggered when the deployment reaches its transactions per second (TPS) limit. |
| [Free Traffic Quota Exhausted](./free_traffic_limit_reached.md) | Triggered when the deployment's free traffic usage reaches a specified threshold. |

### Clients and Messages

| Alert | Description |
| :--- | :--- |
| [Message Drops](./message_loss.md) | Triggered when messages are dropped because a session message queue is full. |
| [Mass Client Unsubscription](./clients_unsubscribe.md) | Triggered when many clients unsubscribe within a short period. |
| [Mass Client Disconnection](./clients_disconnect.md) | Triggered when many clients disconnect within a short period. |

### Network and Security

| Alert | Description |
| :--- | :--- |
| [TLS Certificate Expiring or Expired](./tls_expired.md) | Sent 1 to 30 days before a deployment's TLS certificate expires and after it has expired. |
| [VPC Peering Connection Status Abnormal](./peering_abnormal.md) | Triggered when a VPC peering connection enters an abnormal state. |
| [PrivateLink Status Abnormal](./privatelink_abnormal.md) | Triggered when a PrivateLink endpoint connection enters an abnormal state. |

### Data Integration

| Alert | Description |
| :--- | :--- |
| [Connector Status Abnormal](./connector_abnormal.md) | Triggered when a data integration connector enters an abnormal state. |
| [SQL Matching Failed](./rule_sql_failed.md) | Triggered when SQL matching fails for a data integration rule. |
| [Action Execution Failed](./action_failed.md) | Triggered when a data integration action fails to execute. |
| [Action Status Abnormal](./action_abnormal.md) | Triggered when a data integration action enters an abnormal state. |