SonarSource/sonarqube · error · MessageException

Worker count '%s' is invalid. It must be an integer strictly

Error message

Worker count '%s' is invalid. It must be an integer strictly greater than 0 and less or equal to 10

What it means

CeConfigurationImpl.readWorkerCount validates the sonar.ce.workerCount setting at startup. Compute Engine accepts only an integer from 1 (DEFAULT_WORKER_COUNT) up to 10 (MAX_WORKER_THREAD_COUNT); anything else throws this MessageException and blocks CE startup. The message reminds that the value must be strictly >0 and <=10.

Source

Thrown at server/sonar-ce/src/main/java/org/sonar/ce/configuration/CeConfigurationImpl.java:83

  public CeConfigurationImpl(Configuration configuration, @Nullable WorkerCountProvider workerCountProvider) {
    this.workerCountProvider = workerCountProvider;
    this.gracefulStopTimeoutInMs = configuration.getLong(CE_GRACEFUL_STOP_TIMEOUT.getKey())
      .orElse(Long.parseLong(CE_GRACEFUL_STOP_TIMEOUT.getDefaultValue()));
    this.queuePollingDelay = configuration.getLong(PROPERTY_QUEUE_POLLING_DELAY)
      .orElse(DEFAULT_QUEUE_POLLING_DELAY);
    if (workerCountProvider == null) {
      this.workerCount = DEFAULT_WORKER_COUNT;
      this.workerThreadCount = DEFAULT_WORKER_THREAD_COUNT;
    } else {
      this.workerCount = readWorkerCount(workerCountProvider);
      this.workerThreadCount = MAX_WORKER_THREAD_COUNT;
    }
  }

  private static synchronized int readWorkerCount(WorkerCountProvider workerCountProvider) {
    int value = workerCountProvider.get();
    if (value < DEFAULT_WORKER_COUNT || value > MAX_WORKER_THREAD_COUNT) {
      throw parsingError(value);
    }
    return value;
  }

  private static MessageException parsingError(int value) {
    return MessageException.of(format(
      "Worker count '%s' is invalid. It must be an integer strictly greater than 0 and less or equal to 10",
      value));
  }

  @Override
  public int getWorkerMaxCount() {
    return workerThreadCount;
  }

  @Override
  public int getWorkerCount() {
    if (workerCountProvider != null) {

View on GitHub (pinned to 184c821202)

Solutions

  1. Set sonar.ce.workerCount to an integer between 1 and 10 in sonar.properties.
  2. Remove the property entirely to fall back to the default worker count.
  3. If more throughput is needed, scale horizontally with additional CE nodes instead of raising the per-node cap.
  4. Restart Compute Engine after correcting the property.

Example fix

// sonar.properties before
sonar.ce.workerCount=32
// after
sonar.ce.workerCount=4
Defensive patterns

Strategy: validation

Validate before calling

// shell: validate before putting in sonar.properties
count=<value>
if ! [[ "$count" =~ ^[0-9]+$ ]] || [ "$count" -lt 1 ] || [ "$count" -gt 10 ]; then echo "sonar.ce.workerCount must be 1..10"; exit 1; fi

Try / catch

try {
  int workers = ceConfiguration.getWorkerCount();
} catch (MessageException e) {
  LOG.error("Fix sonar.ce.workerCount (1-10), defaulting", e);
}

Prevention

When it happens

Trigger: Starting SonarQube with sonar.ce.workerCount set to 0, a negative number, a value above 10, or (via the WorkerCountProvider) any out-of-range configured value; note that 0 fails here because the check is value < DEFAULT_WORKER_COUNT (1).

Common situations: Operator tried to 'disable' CE by setting workerCount=0; copy-pasted a sizing recommendation with a huge value (e.g. 32) on a big cluster; typo like -1; setting applied in sonar.properties without realizing the hard cap of 10.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

AI-assisted analysis of SonarSource/sonarqube@184c821202 (2026-09-09). Data as JSON: /api/errors/784bf0500d18ed7f. Report an issue: GitHub.