---
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"@type": TechArticle
"@id": https://www.twilio.com/docs/api/errors/54209#article
headline: "54209: Invalid Map Item key"
url: https://www.twilio.com/docs/api/errors/54209
inLanguage: en
dateModified: 2026-03-11T20:43:38.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 54209: Invalid Map Item key

Log Level: ERROR

## Description

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.