---
page_type: error
code: 54209
message: "54209: Invalid Map Item key"
level: ERROR
product: Sync
---

## Error - 54209

### Sync: Invalid Map Item key

The Map Item key must be a string with length 1-256.

#### Possible Causes

- The value supplied by the Map Key parameter contains an empty string.
- The string supplied by the Map Key parameter exceeds 256 characters.

#### Possible Solutions

- Confirm a valid Map Key parameter is being passed in your request.