alibaba/arthas · error · ApiException

parse request failed: request body is empty

Error message

parse request failed: request body is empty

What it means

Thrown by HttpApiHandler.parseRequest when the HTTP request body is blank (null, empty, or whitespace only). The Arthas HTTP API expects a JSON body containing at minimum an 'action' field; an empty body cannot be parsed into an ApiRequest.

Source

Thrown at core/src/main/java/com/taobao/arthas/core/shell/term/impl/http/api/HttpApiHandler.java:105

            logger.error("arthas process http api request error: " + request.uri() + ", request body: " + requestBody, e);
        }
        if (result == null) {
            result = createResponse(ApiState.FAILED, "The request was not processed");
        }
        result.setRequestId(requestId);

        byte[] jsonBytes = JSON.toJSONBytes(result, JSON_FILTERS);

        // create http response
        DefaultFullHttpResponse response = new DefaultFullHttpResponse(request.protocolVersion(),
                HttpResponseStatus.OK, Unpooled.wrappedBuffer(jsonBytes));
        response.headers().set(HttpHeaderNames.CONTENT_TYPE, "application/json; charset=utf-8");
        return response;
    }

    private ApiRequest parseRequest(String requestBody) throws ApiException {
        if (StringUtils.isBlank(requestBody)) {
            throw new ApiException("parse request failed: request body is empty");
        }
        try {
            //ObjectMapper objectMapper = new ObjectMapper();
            //return objectMapper.readValue(requestBody, ApiRequest.class);
            return JSON.parseObject(requestBody, ApiRequest.class);
        } catch (Exception e) {
            throw new ApiException("parse request failed: " + e.getMessage(), e);
        }
    }

    private ApiResponse processRequest(ChannelHandlerContext ctx, ApiRequest apiRequest) {

        String actionStr = apiRequest.getAction();
        try {
            if (StringUtils.isBlank(actionStr)) {
                throw new ApiException("'action' is required");
            }
            ApiAction action;

View on GitHub (pinned to 21cf2e9ba5)

Solutions

1. Send a valid JSON body: curl -X POST http://localhost:8563/api -d '{"action":"init_session"}'.
2. Ensure the client sets Content-Type: application/json and includes a non-empty body.
3. Check that no intermediary proxy strips POST bodies.

Example fix

# before
curl -X POST http://localhost:8563/api
# -> parse request failed: request body is empty

# after
curl -X POST http://localhost:8563/api \
  -H 'Content-Type: application/json' \
  -d '{"action":"init_session"}'

// Client-side: ensure non-empty body before sending
String body = buildRequestBody(apiRequest);
if (body == null || body.trim().isEmpty()) {
    throw new IllegalArgumentException("Request body must not be empty");
}

When it happens

Trigger: POSTing to the Arthas HTTP API endpoint (default :8563) with an empty request body, or sending a request with Content-Length: 0.

Common situations: Misconfigured REST client that omits the body. Curl invocation missing the -d flag. Proxy or load balancer stripping the body.

Related errors

• parse request failed: {}
• 'action' is required
• 'sessionId' is required
• 'consumerId' is required
• Conversion from JSON to {type} failed

AI-assisted analysis of alibaba/arthas@21cf2e9ba5 (2026-08-14). Data as JSON: /api/errors/d113538b5277d4da. Report an issue: GitHub.