# How to Fix INVALID_PROPERTY_VALUE: "A numerical value is expected to follow the negative sign" in WhatsApp Flows
Author: Prashant Jangid
Author URL: https://www.heltar.com/blogs/author/prashant-jangid
Published: 2025-07-01
Category: Troubleshoot
Category URL: https://www.heltar.com/blogs/category/troubleshoot
Tags: WhatsApp Flows Error
Tag URLs: WhatsApp Flows Error (https://www.heltar.com/blogs/tag/whatsapp-flows-error)
URL: https://www.heltar.com/blogs/how-to-fix-invalidpropertyvalue-a-numerical-value-is-expected-to-follow-the-negative-sign-in-whatsapp-flows-cmckvm8ub002k2c4a0eqhdutm

If you're seeing the error:

**INVALID\_PROPERTY\_VALUE**

**A numerical value is expected to follow the negative sign.**

Here’s the quick fix:

Ensure a valid number follows the minus (-) sign in your expression.

The expression in your If condition must not include misplaced operators or incomplete syntax.

## What's Going Wrong?

In this payload:

```
{
  "type": "If",
  "condition": "${data.val} ) -a",
  "then": [...]
}
```

There are multiple issues:

1. **${data.val} )** has a mismatched closing parenthesis.

2. **-a** is not a valid number or operand. The minus sign expects a number like **-5** or a proper subtraction expression like **${data.val} - 2**.


## How to Fix It

Clean up the expression to make it syntactically valid. Here's a corrected version assuming you want to check if **data.val** is greater than **-1**:

```
{
  "type": "If",
  "condition": "${data.val} > -1",
  "then": [...]
}
```

Or if you're comparing against another variable:

```
{
  "type": "If",
  "condition": "${data.val} - ${data.anotherVal} > 0",
  "then": [...]
}
```

## Developer Tips

- Always wrap dynamic values with ${...}.

- Every operator (+, -, >, etc.) must have valid operands on both sides.

- Watch for extra parentheses or misplaced characters—these are common sources of parsing errors.

- Use tools or formatters to spot broken expressions early.


## TL;DR

The minus sign must be followed by a valid number or a complete subtraction.

 -a: Invalid

 -1, ${data.val} - 2: Valid

For more troubleshooting insights related to WhatsApp Business API, check out [heltar.com/blogs](https://www.heltar.com/blogs).


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