eclipse-vertx/vert.x · error · IllegalArgumentException

Invalid ${value}

Error message

Invalid ${value}

What it means

Static configuration validation in EpollTransport.setPendingFastOpenRequestsThreshold: the TCP_FASTOPEN pending-connections threshold must be a valid value (positive). The message is a generic 'Invalid <value>' sentinel; the input at fault is the int passed to this global setter.

Source

Thrown at vertx-core/src/main/java/io/vertx/core/impl/transports/EpollTransport.java:56

  private static volatile int pendingFastOpenRequestsThreshold = 256;

  /**
   * Return the number of of pending TFO connections in SYN-RCVD state for TCP_FASTOPEN.
   * <p>
   * {@see #setPendingFastOpenRequestsThreshold}
   */
  public static int getPendingFastOpenRequestsThreshold() {
    return pendingFastOpenRequestsThreshold;
  }

  /**
   * Set the number of pending TFO connections in SYN-RCVD state for TCP_FASTOPEN
   * <p/>
   * If this value goes over a certain limit the server disables all TFO connections.
   */
  public static void setPendingFastOpenRequestsThreshold(int value) {
    if (value < 0) {
      throw new IllegalArgumentException("Invalid " + value);
    }
    pendingFastOpenRequestsThreshold = value;
  }

  public EpollTransport() {
  }

  @Override
  public boolean supportsDomainSockets() {
    return true;
  }

  @Override
  public SocketAddress convert(io.vertx.core.net.SocketAddress address) {
    if (address.isDomainSocket()) {
      return new DomainSocketAddress(address.path());
    } else {
      return Transport.super.convert(address);

View on GitHub (pinned to fb308bd8c3)

Solutions

1. Pass a positive threshold value (default 256)
2. Validate externally sourced values before setting the global

When it happens

Trigger: Thrown at vertx-core/src/main/java/io/vertx/core/impl/transports/EpollTransport.java:56 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of eclipse-vertx/vert.x@fb308bd8c3 (2026-09-06). Data as JSON: /api/errors/2a0f0af30d9cfe50. Report an issue: GitHub.