maven: Target server failed to respond

Was getting an exception with the maven (3.2.2) wagon plugin version 2.6.

Looking deeper, this plugin uses wagon-provider 2.6 which depends on httpclient 4.3.  This can be seen here: http://repo1.maven.org/maven2/org/apache/maven/wagon/wagon-providers/2.6/wagon-providers-2.6.pom
and looks like this:

 ...  
 <dependencyManagement>  
 <dependencies>  
 <dependency>  
 <groupId>org.apache.httpcomponents</groupId>  
 <artifactId>httpclient</artifactId>  
 <version>4.3.1</version>  
 </dependency> ...  

The exception seen when running a maven build looks similar to this:

Caused by: org.apache.maven.wagon.providers.http.httpclient.NoHttpResponseException: The target server failed to respond

This bug: https://issues.apache.org/jira/browse/HTTPCLIENT-1531

indicates that there is a bug with httpclient in the versions 4.3 >= 4.3.4 & 4.4 Alpha1 when using a proxy (like apache httpd) between the client and server, without client authentication enabled.  The bug causes the no response exception later in the wagon plugin called via the WagonRepositoryConnector class.

Specifically, the bug occurs when authentication is disabled because as of 4.3.x the MainClientExec.java has a function to create tunnel to target, (createTunnelToTarget) that when authentication is disabled, the for loop does not exit properly and the request is never completed.

http://svn.apache.org/repos/asf/httpcomponents/httpclient/branches/4.3.x/httpclient/src/main/java/org/apache/http/impl/execchain/MainClientExec.java


In our case, just upgrading to 3.2.5 worked.   Another option is to include the lightweight http provider with wagon configuration.  this uses the Java HTTP libraries instead of apache's implementation.