# 40013: Invalid message data or encoding

Identifier: `invalid_data_or_encoding`



A message was rejected because its data was of an unsupported type, or because the encoding declared for the data could not be applied or reversed.

## What you should do

Publish data of a supported type. Message data must be a string, binary data (such as a Buffer, ArrayBuffer, or TypedArray), or a plain object or array that serializes to JSON. Convert other types, such as `Date`, `Map`, or `Set`, to one of these before publishing. If you set an `encoding` yourself, make sure it correctly describes the data.

## Why it happens

The SDK couldn't serialize the message payload, or the declared encoding couldn't be applied or reversed. This usually means the data was of a type the SDKs don't support, so it can't be represented as JSON or MessagePack.

## What you'll see

The error is reported with code 40013 and HTTP status 400. The message is typically `Data type is unsupported`, and it is often raised by the SDK before the message is sent.