Comfy-Org/ComfyUI · error · UploadError

UNSUPPORTED_FIELD

UNSUPPORTED_FIELD

Error message

Client-provided 'id' is not supported. Asset IDs are assigned by the server.

What it means

Raised from the HTTP >=400 branch (comfy_api_nodes/util/client.py:823) via _friendly_http_message only inside its own except: if formatting the message raises unexpectedly (e.g. json.dumps fails on an exotic body), the formatter falls back to 'HTTP {status}: Unknown error'. The original body is still in the request log.

Source

Thrown at app/assets/api/upload.py:134

                        chunk = await field.read_chunk(8 * 1024 * 1024)
                        if not chunk:
                            break
                        f.write(chunk)
                        file_written += len(chunk)
            except Exception:
                delete_temp_file_if_exists(tmp_path)
                raise UploadError(
                    500, "UPLOAD_IO_ERROR", "Failed to receive and store uploaded file."
                )

        elif fname == "tags":
            tags_raw.append((await field.text()) or "")
        elif fname == "name":
            provided_name = (await field.text()) or None
        elif fname == "user_metadata":
            user_metadata_raw = (await field.text()) or None
        elif fname == "id":
            raise UploadError(
                400,
                "UNSUPPORTED_FIELD",
                "Client-provided 'id' is not supported. Asset IDs are assigned by the server.",
            )
        elif fname == "mime_type":
            provided_mime_type = ((await field.text()) or "").strip() or None
        elif fname == "preview_id":
            provided_preview_id = ((await field.text()) or "").strip() or None
    if not file_present and not (provided_hash and provided_hash_exists):
        raise UploadError(
            400, "MISSING_FILE", "Form must include a 'file' part or a known 'hash'."
        )

    if (
        file_present
        and file_written == 0
        and not (provided_hash and provided_hash_exists)
    ):

View on GitHub (pinned to 1c6d8d45b3)

Solutions

Inspect the logged response_content — the message deliberately omits the body
Reproduce with curl to see the raw response for the same request
Report the provider/status combination upstream if reproducible, since the body defeated the formatter

Defensive patterns

Strategy: try-catch

Try / catch

try:
    result = await sync_op(...)
except Exception as e:
    if re.match(r"HTTP \d+: Unknown error", str(e)):
        body = request_logger.last_response_content  # message omits the body
        diagnose(body)
    else:
        raise

Prevention

Reproduce the failing call with curl to see the raw response the formatter could not handle
Never rely on this message alone — the body exists only in the request log

When it happens

Trigger: Extremely rare: a >=400 response whose body type breaks both the dict branch (json.dumps failure, e.g. non-serializable content) and the str() path; defensive last resort in _friendly_http_message's try/except.

Common situations: Almost never seen in practice; possible with binary bodies misparsed into the JSON branch or provider returning a body object whose repr raises.

Related errors

AI-assisted analysis of Comfy-Org/ComfyUI@1c6d8d45b3 (2026-08-14). Data as JSON: /api/errors/ce74c35b67eba5a3. Report an issue: GitHub.