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Transporter Known Issues

This page lists known issues related to various transporters.

The jdk (Java HttpClient) Transporter

Given this transporter uses the Java HttpClient (available since Java 11), it is the user's best interest to use latest patch version of Java, as HttpClient is getting bugfixes regularly.

Known issues:

  • Does not properly support aether.transport.http.requestTimeout configuration prior Java 26, see JDK-8208693
  • No TLS Proxy support, see here
  • No SOCKS proxy support, see JDK-8214516
  • In case of Proxy TLS tunneling, to enable Proxy Basic authentication, one must use jdk.http.auth.tunneling.disabledScheme Java System Property, see here. Java versions since 8u111 have this property set to value “Basic” making HTTP Basic authentication disabled, see here. To enable HTTP Basic authentication for Proxy TLS tunneling, one must set jdk.http.auth.tunneling.disabledScheme to empty string, e.g. by adding -Djdk.http.auth.tunneling.disabledScheme="" JVM argument.
  • Preemptive basic authentication is only supported on Java 16 and below and on Java 24 and above, see JDK-8326949.
  • HTTP/2 GOAWAY frames incorrectly handled in Java < 17.0.17, Java 18 till Java < 21.0.8 and Java 22 till Java < 24, see JDK-8335181.
  • HTTP/2 GOAWAY does not lead to proper connection shutdown, see JDK-8385131.
  • HTTP/3 is only supported with Java 26 and above.

Maven 4 uses this transport by default for HTTP(S) protocol.

The apache (Apache HttpClient) Transporter

Transporter based on Apache HttpClient 4.

To use this transporter in Maven 4, you need to specify -Dmaven.resolver.transport=apache user property.

Known issues:

  • Does neither support HTTP/2 nor HTTP/3

The jetty (Jetty HttpClient) Transporter

Transporter based on Jetty HttpClient. It requires Java 17 or above.

In Maven 4 this transport is not available by default (is not bundled). To use it, you need to add org.apache.maven.resolver.transport:transport-http-jetty artifact with its runtime dependencies to /lib directory of Maven. Once added to core classpath, it will take over the role of default transport.

Known issues:

The url (Consumer Only) Transporter

Special Transport with limited HTTP capabilities. The main use case of this transport is outside of Maven, in apps that are Java 8+ and integrate Resolver only for consumption purposes. Before this transport, the only option was to either bump Java level to 11 and use JDK transport, or to use the heavyweight Apache HttpClient transport, which is not always desirable.

Supported features:

  • Implemented using java.net.HttpURLConnection class
  • HTTP 1.1 support, only for GET and HEAD methods
  • HTTP redirects (max 5)
  • HTTP gzip and deflate compression support
  • HTTP Basic authentication (w/ preemptive support)
  • HTTP proxy support (w/ Basic proxy authentication)
  • HTTP auth caching (lowers “known to be needed” HTTP round-trips)
  • Smart checksums (extracts checksums from response headers, potentially halves the HTTP round-trips)
  • Timeout for connection and request

This transport is not a fully functional transport, and should be handled as such. It is quite usable in artifact consumption scenarios, but it is not suitable for artifact deployment.

Known issues:

  • Does neither support HTTP/2 nor HTTP/3
  • Supports only GET/HEAD, usable only for artifact consumption
  • Is and will never be present in Maven; is meant for applications integrating Resolver