# Error Handling

This page provides a comprehensive guide to handling errors returned by the PMS API. Each error includes an explanation, probable causes, and example code for resolving it in various programming languages.

## Overview of Error Handling

The PMS API uses standard HTTP status codes to indicate the success or failure of API requests. The most common error categories are:

- **201 (Success)**: A successful response with no body.
- **400 (Bad Request)**: The request could not be understood or was missing required parameters.
- **401 (Unauthorized)**: Authentication failed or the user does not have permissions.
- **404 (Not Found)**: The requested resource could not be found.
- **500 (Internal Server Error)**: An unexpected error occurred on the server.


## Error Categories

### 1. Validation Errors (400 Bad Request)

**Description:**
Occurs when the input parameters are invalid or missing.

**Example Error Response:**


```json
 "status": 400,
  "detail": "Errors occurred while processing the request.",
  "errors": [
    {
      "name": "roomNumber",
      "reason": "RoomNumberConflict - The room you are trying to check in is already occupied with a guest from a different company. Please verify the room number and resubmit."
    }
  ]
```

**Probable Causes:**

- Missing required fields in the request body.


**How to Handle:**

Validate input parameters before sending the request.

### 2. Authentication Errors (401 Unauthorized)

**Description:**
Occurs when the API key or token is invalid, expired, or missing.

**Example Error Response:**


```json
{
  "message": "Unauthorized"
}
```

**Probable Causes:**

- Missing `Authorization` header.
- Expired or incorrect API token.


**How to Handle:**

1. Ensure the token is included in the `Authorization` header.
2. Refresh the token if it has expired.


### 3. Internal Server Errors (500 Internal Server Error)

**Description:**
Occurs when the API encounters an unexpected issue.

**Example Error Response:**


```json
{    
  "errorCode": "INTERNAL_ERROR",    
  "message": "An unexpected error occurred. Please try again later." 
}
```

**Probable Causes:**

- Temporary server issue.
- Unhandled exception on the server.


**How to Handle:**

1. Retry the request after a short delay.
2. Contact support if the issue persists.


## General Best Practices for Error Handling

- **Log Errors:** Always log error details to help with debugging.
- **Implement Retries:** Use exponential backoff for retrying requests.
- **Graceful Failures:** Provide fallback options or friendly error messages.
- **Documentation:** Always refer to the latest API documentation for error codes and responses.