eclipse-vertx/vert.x · error · IllegalArgumentException

protocolVersion must not be null

Error message

protocolVersion must not be null

What it means

Null guard in HttpClientOptions.setProtocolVersion: the HttpVersion argument is null. The client needs a concrete default version (HTTP_1_1, HTTP_2, H2C, HTTP_3) to build requests, so a null value is rejected immediately rather than silently defaulted.

Source

Thrown at vertx-core/src/main/java/io/vertx/core/http/HttpClientOptions.java:759

  /**
   * Get the protocol version.
   *
   * @return the protocol version
   */
  public HttpVersion getProtocolVersion() {
    return protocolVersion;
  }

  /**
   * Set the protocol version.
   *
   * @param protocolVersion the protocol version
   * @return a reference to this, so the API can be used fluently
   */
  public HttpClientOptions setProtocolVersion(HttpVersion protocolVersion) {
    if (protocolVersion == null) {
      throw new IllegalArgumentException("protocolVersion must not be null");
    }
    this.protocolVersion = protocolVersion;
    return this;
  }

  /**
   * Set the maximum HTTP chunk size
   * @param maxChunkSize the maximum chunk size
   * @return a reference to this, so the API can be used fluently
   */
  public HttpClientOptions setMaxChunkSize(int maxChunkSize) {
    http1Config.setMaxChunkSize(maxChunkSize);
    return this;
  }

  /**
   * Returns the maximum HTTP chunk size
   * @return the maximum HTTP chunk size

View on GitHub (pinned to fb308bd8c3)

Solutions

1. Pass a non-null HttpVersion (HTTP_1_1 is the conventional default)
2. Treat null in external configuration as 'unset' and skip calling the setter

When it happens

Trigger: Thrown at vertx-core/src/main/java/io/vertx/core/http/HttpClientOptions.java:759 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/94c04ef665a0c816. Report an issue: GitHub.