When working with WhatsApp API, encountering an INVALID_FLOW_JSON error can be frustrating. This error occurs when the provided Flow JSON is not properly structured, making it unreadable by the system. Since JSON errors prevent parsing, pinpointing the exact issue can be difficult. This guide will help you troubleshoot and fix common mistakes.

Common Causes of INVALID_FLOW_JSON Errors

1. Incorrect JSON Version

The specified version in your JSON might not be supported by WhatsApp. Always check the latest API documentation to ensure you are using a compatible version.

2. Invalid JSON Format

There might be missing or misplaced brackets, commas, or incorrect key-value pairs.

Example of Invalid JSON:

{
    "routing_model": {},
    "screens": [
        ...
    ],,
}

Fixed JSON:

{
    "routing_model": {},
    "screens": [
        ...
    ]
}

Solution: Remove extra commas, misplaced brackets, and ensure proper key-value formatting.

3. Schema Changes

WhatsApp updates its API regularly, and older schemas may become obsolete. If your JSON was working before but now returns an error, verify that all fields comply with the latest schema.

4. Malformed Flow Structure

The flow JSON must follow a structured format. If any required fields are missing, the API rejects it.

Example of Invalid JSON:

{
    "routing_model": {
    "screens": [
        ...
}

Fixed JSON:

{
    "routing_model": {},
    "screens": [
        ...
    ]
}

Solution: Ensure that every { has a } and every [ has a ], and all required fields are present.

5. Internal API Issues

Sometimes, the issue is on WhatsApp’s end due to temporary bugs or server-side updates. If you have confirmed that your JSON is correct, try again later or check WhatsApp’s status page for any ongoing issues.

6. Incorrect Data Types

JSON values must follow correct data types:

  • Strings must be enclosed in double quotes (")

  • Booleans should be true or false (without quotes)

  • Numbers should not be enclosed in quotes

Example of Invalid JSON:

{
    "is_active": "true"
}

Fixed JSON:

{
    "is_active": true
}

Solution: Use correct data types and proper syntax.

7. Using Single Quotes Instead of Double Quotes

JSON requires double quotes for keys and string values.

Example of Invalid JSON:

{
    'key': 'value'
}

Fixed JSON:

{
    "key": "value"
}

Solution: Replace single quotes (') with double quotes (").

8. Invalid Characters or Formatting Issues

Copying and pasting JSON from different sources can introduce hidden characters or incorrect indentation.

Solution: Use a JSON validator like:

  • JSONLint

  • [VS Code's built-in JSON formatter]

9. Malformed Objects or Arrays

Ensure objects ({}) and arrays ([]) follow the expected structure defined by the API.

Tips to Debug and Prevent Schema Errors

  • Review the official documentation to understand property constraints.

  • Use a JSON schema validator to catch errors early.

  • Ensure properties are placed in the correct hierarchy.

  • If using a coding environment, enable JSON linting.

  • Ensure the structure follows API requirements.

For more troubleshooting insights related to WhatsApp Business API, check out heltar.com/blogs.