# invalid_base64

> `contentBase64` is not valid base64.

**Invalid base64** · HTTP 400

## What it means

`contentBase64` is not valid base64.

## What to do

Encode the file's bytes with standard base64 (no data: prefix, no line breaks).

## Example

```json
{
  "type": "https://api.bymundi.com/problems/invalid_base64",
  "title": "Invalid base64",
  "status": 400,
  "detail": "`contentBase64` is not valid base64.",
  "code": "invalid_base64",
  "requestId": "req_…"
}
```

How to read any error: [Errors guide](https://api.bymundi.com/docs/guides/errors.md).