# Fixing INVALID_SCREEN_DATA in WhatsApp Flows: Missing the definition of property ‘type’. Here’s the Fix
Author: Prashant Jangid
Author URL: https://www.heltar.com/blogs/author/prashant-jangid
Published: 2025-05-16
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/fixing-invalidscreendata-in-whatsapp-flows-forgot-the-type-heres-what-you-missed-cmaqol4bj008gkwl4fii6nrjw

Getting this error?

**INVALID\_SCREEN\_DATA**

**Missing the definition of property ‘type’.**

This one’s simple: every field in your data model must declare its type. No type, no schema, no Flow.

## The Fix (TL;DR):

Add a "type" to every property in your data model.

### Correct:

```
"data": {
  "name": {
    "type": "string"
  }
}
Incorrect:
```

"data": {

"name": {}

}

## Why This Happens?

In WhatsApp Flows, the data section defines the structure of variables your screen will use. The schema expects a clear definition of what each field is — a string, number, object, array, or boolean.

Without the type property, the Flow builder has no clue how to handle the field — and throws the INVALID\_SCREEN\_DATA error.

### Corrected Example

```
"data": {
  "name": {
    "type": "string"
  },
  "__example__": {
    "name": "John Doe"
  }
}
```

Now the Flow knows name is a string and can validate it properly.

### Best Practices

- Always include a "type" for every data field, even for nested properties.

- Use "\_\_example\_\_" at the top level to provide sample values.

- Validate your schema incrementally to catch missing types early.


This is one of the most common mistakes in Flow development — and one of the easiest to fix. Every field needs a type. Once you get that right, the rest falls into place. For more troubleshooting insights related to WhatsApp Business API, check out [heltar.com/blogs](https://www.heltar.com/blogs).


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