# API03001: Invalid Request Format

## What This Means[​](#what-this-means "Direct link to What This Means")

The request sent to the server was not in the expected format. The server couldn't understand what the POS was asking for because the request structure was incorrect.

## Common Causes[​](#common-causes "Direct link to Common Causes")

* **Corrupted data** — Data was corrupted before sending
* **Software bug** — An issue in the POS application
* **Proxy interference** — A proxy or firewall modified the request
* **Character encoding issues** — Special characters weren't encoded properly

## Server Error Mapping[​](#server-error-mapping "Direct link to Server Error Mapping")

This error code is triggered when the server returns:

| Server Code | Source                         |
| ----------- | ------------------------------ |
| HTTP 400    | Any server response (fallback) |

## How to Fix[​](#how-to-fix "Direct link to How to Fix")

### 1. Retry the Action[​](#1-retry-the-action "Direct link to 1. Retry the Action")

Sometimes this is a one-time glitch:

* Wait a moment and try again
* Refresh the POS and retry

### 2. Check for Special Characters[​](#2-check-for-special-characters "Direct link to 2. Check for Special Characters")

If you're entering data with special characters:

* Try removing emojis or unusual symbols
* Use standard characters for product names, etc.

### 3. Update the POS[​](#3-update-the-pos "Direct link to 3. Update the POS")

Ensure you're running the latest version:

* Check for app updates
* Update the WCPOS plugin on your server

### 4. Check Network Configuration[​](#4-check-network-configuration "Direct link to 4. Check Network Configuration")

If you're behind a proxy:

* Verify the proxy isn't modifying requests
* Check firewall rules
* Try accessing from a different network

### 5. Report the Issue[​](#5-report-the-issue "Direct link to 5. Report the Issue")

If this happens consistently:

* Note what action triggers the error
* Check browser console for details (web version)
* Report on [GitHub](https://github.com/wcpos) with reproduction steps

## Related Errors[​](#related-errors "Direct link to Related Errors")

* [API03002](/error-codes/API03002.md) — Missing Required Parameters
* [API03003](/error-codes/API03003.md) — Invalid Parameter Value