What it means
content.data did not decode.
How to handle it
Encode the content bytes as valid base64; accepted padding and data-URL variants do not make invalid bytes valid.
Wire contract
| Code | invalid_base64 |
|---|---|
| Class | invalid_request |
| HTTP status | 400 |
| Meta keys | None |
| Raised | Yes |
The response uses the standard {"error": {…}} envelope. Branch on error.code, not the human-readable message. Preserve request_id when reporting a failure.