eclipse-vertx/vert.x · error · DecodeException

${e.getMessage()}

Error message

${e.getMessage()}

What it means

JsonCodec.fromStream decodes JSON from an InputStream by reading all bytes and delegating to fromBuffer. If the underlying stream throws an IOException while reading, it is wrapped in a DecodeException whose message is the IOException's message.

Source

Thrown at vertx-core/src/main/java/io/vertx/core/spi/json/JsonCodec.java:96

  }

  /**
   * Decode JSON from the given {@link InputStream} to an object of the specified type.
   * <p>
   * The input is expected to be UTF-8 encoded.
   * <p>
   * The codec does not close or flush the stream; the caller retains ownership.
   *
   * @param in    the input stream containing UTF-8 encoded JSON
   * @param clazz the required object's class
   * @return the decoded instance
   * @throws DecodeException anything preventing the decoding
   */
  default <T> T fromStream(InputStream in, Class<T> clazz) throws DecodeException {
    try {
      return fromBuffer(Buffer.buffer(in.readAllBytes()), clazz);
    } catch (IOException e) {
      throw new DecodeException(e.getMessage(), e);
    }
  }

  /**
   * Decode JSON from the given {@link InputStream}.
   * <p>
   * The input is expected to be UTF-8 encoded.
   * <p>
   * The codec does not close or flush the stream; the caller retains ownership.
   *
   * @param in the input stream containing UTF-8 encoded JSON
   * @return a JSON element which can be a {@link JsonArray}, {@link JsonObject}, {@link String}, etc.
   * @throws DecodeException anything preventing the decoding
   */
  default Object fromStream(InputStream in) throws DecodeException {
    return fromStream(in, Object.class);
  }

View on GitHub (pinned to fb308bd8c3)

Solutions

1. Check stream availability/lifecycle before decoding (ensure the source connection/file is open and readable).
2. Read bytes into a Buffer first yourself and use fromBuffer, handling IOException where you can retry.
3. Retry the fetch of the stream (network blips) rather than treating it as a JSON syntax problem.
4. Note: a JSON syntax error surfaces directly from fromBuffer as DecodeException — distinguish read failures (wrapped IOException) from parse failures.

Example fix

// before
MyDto dto = codec.fromStream(in, MyDto.class); // IOException wrapped as DecodeException
// after
byte[] bytes;
try {
  bytes = in.readAllBytes();
} catch (IOException e) {
  bytes = retryFetch();
}
MyDto dto = codec.fromBuffer(Buffer.buffer(bytes), MyDto.class);

// read bytes yourself so IOException is handled where you can retry
byte[] bytes = in.readAllBytes();
codec.fromBuffer(Buffer.buffer(bytes), MyDto.class);

try {
  return codec.fromStream(in, MyDto.class);
} catch (DecodeException e) {
  if (e.getCause() instanceof java.io.IOException) {
    throw new java.io.UncheckedIOException((java.io.IOException) e.getCause()); // read problem, retry upstream
  }
  throw e; // actual JSON parse problem
}

When it happens

Trigger: Calling fromStream(in, clazz) where the InputStream fails mid-read: a closed socket, broken file handle, or interrupted pipe.

Common situations: Reading JSON from a network stream that the peer closed; reading a file that was deleted/truncated while streaming; wrapping a HttpURLConnection input stream after a connection reset.

Understand the failure class

Background: "failed to unmarshal" / json.Unmarshal errors: why parsing a response into a Go struct fails and how to fix it — this error's family across 23 libraries.

Related errors

• Failed to decode:${e.getMessage()}
• ${e.getMessage()}
• workerPoolSize must be > 0
• Failed to unpack ${url}
• Failed to copy ${from} to ${to}

AI-assisted analysis of eclipse-vertx/vert.x@fb308bd8c3 (2026-09-06). Data as JSON: /api/errors/10796e2e74cb62a7. Report an issue: GitHub.