Proxy Trouble After a Maven 3.9 Upgrade

Maven 3.9.0 changed the default Resolver HTTP transport from Wagon to native HTTP. An old Wagon-specific workaround can stop controlling repository requests even if the proxy URL did not change.

Check the running Maven version, active proxy configuration in settings.xml and selected Resolver transport. A JVM accepting a -D argument does not establish that its HTTP client uses that property.

For Maven 3.9 releases supporting the documented selector, this comparison requests Wagon:

mvn -Dmaven.resolver.transport=wagon dependency:resolve

Run it only when you intend dependency downloads for the same project and approved endpoint. It is a network operation, not a configuration query. A different result narrows the implementation difference; it does not make Wagon the permanent answer. Check supported names before using such a selector with Maven 4 or a future release.

Keep the actual challenge and error stage. Browser authentication does not establish NTLM support in either Maven transport. A 407, a certificate rejection, an unavailable repository and a timeout need different fixes. Record the version, transport, proxy method and smallest reproducing operation before adding pool/time flags or changing mirrors and artifact versions.