google/gson · critical · JsonParseException

Failed parsing JSON source to Json

Error message

Failed parsing JSON source to Json

What it means

JsonStreamParser.next() delegates to Streams.parse and catches StackOverflowError/OutOfMemoryError, rethrowing as JsonParseException. It is the streaming counterpart of error 42: the next value in a concatenated stream is too large or too deeply nested for the JVM.

Source

Thrown at gson/src/main/java/com/google/gson/JsonStreamParser.java:91

  /**
   * Returns the next available {@link JsonElement} on the reader. Throws a {@link
   * NoSuchElementException} if no element is available.
   *
   * @return the next available {@code JsonElement} on the reader.
   * @throws JsonParseException if the incoming stream is malformed JSON.
   * @throws NoSuchElementException if no {@code JsonElement} is available.
   * @since 1.4
   */
  @Override
  public JsonElement next() throws JsonParseException {
    if (!hasNext()) {
      throw new NoSuchElementException();
    }

    try {
      return Streams.parse(parser);
    } catch (StackOverflowError | OutOfMemoryError e) {
      throw new JsonParseException("Failed parsing JSON source to Json", e);
    }
  }

  /**
   * Returns true if a {@link JsonElement} is available on the input for consumption
   *
   * @return true if a {@link JsonElement} is available on the input, false otherwise
   * @throws JsonParseException if the incoming stream is malformed JSON.
   * @since 1.4
   */
  @Override
  public boolean hasNext() {
    synchronized (lock) {
      try {
        return parser.peek() != JsonToken.END_DOCUMENT;
      } catch (MalformedJsonException e) {
        throw new JsonSyntaxException(e);
      } catch (IOException e) {

View on GitHub (pinned to 8b8628c656)

Solutions

1. Increase -Xss/-Xmx for legitimate workloads.
2. Enforce per-record size and depth caps before parsing.
3. Use a bounded JsonReader pass and skip/abort oversized records.
4. Switch from tree-based Streams.parse to direct token streaming for memory control.

Example fix

// before
while (parser.hasNext()) {
  JsonElement e = parser.next();
}

// after (bounded reader per record)
try (JsonReader r = new JsonReader(reader)) {
  r.setStrictness(Strictness.STRICT);
  // walk tokens, enforce MAX_DEPTH and MAX_BYTES
}

// enforce per-record size before adding to stream
if (recordBytes > MAX_RECORD_BYTES) skip();

try {
  JsonElement e = parser.next();
} catch (JsonParseException ex) {
  if (ex.getCause() instanceof StackOverflowError
      || ex.getCause() instanceof OutOfMemoryError) {
    // log and skip oversized record rather than abort stream
  } else throw ex;
}

When it happens

Trigger: Iterating a JsonStreamParser over a stream where one element is pathologically nested or huge; processing NDJSON records where a single record overflows memory.

Common situations: Log/event ingestion pipelines; NDJSON consumers; adversarial input in a streaming endpoint.

Related errors

• Failed parsing JSON source: {reader} to Json
• No time zone indicator
• Invalid time zone indicator {timezoneIndicator}
• Failed to parse date [{input}]: {fail.getMessage()}
• {value}

AI-assisted analysis of google/gson@8b8628c656 (2026-08-04). Data as JSON: /data/errors/6a67d06d653c2709.json. Report an issue: GitHub.