What could be causing 'error transferring file' in maven?

Question

I have installed maven 2.2.1 on my debian machine and getting the following error

[WARNING] repository metadata for: 'org.apache.maven.plugins' could not be retrieved  from repository: central due to an error: Error transferring file: repository.exoplatform.org

What I have been able to find relating to this problem is its typically caused by not having proxy settings correctly configured or a firewall blocking traffic, but I dont have either on this machine. Also, I have the same settings file on my windows machine and it works fine.

Any suggestions would be greatly appreciated as I am stumped.

exo@melb-web:~/test$ mvn -v
Apache Maven 2.2.1 (r801777; 2009-08-07 05:16:01+1000)
Java version: 1.5.0_22
Java home: /usr/local/bin/jdk1.5.0_22/jre
Default locale: en_AU, platform encoding: UTF-8
OS name: "linux" version: "2.6.22-3-amd64" arch: "i386" Family: "unix"
exo@melb-web:~/test$ mvn archetype:generate
[INFO] Scanning for projects...
[INFO] Searching repository for plugin with prefix: 'archetype'.
[INFO] org.apache.maven.plugins: checking for updates from central
[WARNING] repository metadata for: 'org.apache.maven.plugins' could not be retrieved from repository: central due to an error: Error transferring file: repository.exoplatform.org
[INFO] Repository 'central' will be blacklisted
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] The plugin 'org.apache.maven.plugins:maven-archetype-plugin' does not exist or no valid version could be found
[INFO] ------------------------------------------------------------------------
[INFO] For more information, run Maven with the -e switch
[INFO] ------------------------------------------------------------------------
[INFO] Total time: < 1 second
[INFO] Finished at: Wed Jun 30 10:18:33 EST 2010
[INFO] Final Memory: 2M/136M
[INFO] ------------------------------------------------------------------------

* EDIT *

I tried removing the settings.xml and generating a new maven project. I got the following

exo@melb-web:~/test$ mvn archetype:generate
[INFO] Scanning for projects...
[INFO] Searching repository for plugin with prefix: 'archetype'.
[INFO] org.apache.maven.plugins: checking for updates from central
[WARNING] repository metadata for: 'org.apache.maven.plugins' could not be retrieved from repository: central due to an error: Error transferring file: repo1.maven.org
[INFO] Repository 'central' will be blacklisted
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] The plugin 'org.apache.maven.plugins:maven-archetype-plugin' does not exist or no valid version could be found
[INFO] ------------------------------------------------------------------------
[INFO] For more information, run Maven with the -e switch
[INFO] ------------------------------------------------------------------------
[INFO] Total time: < 1 second
[INFO] Finished at: Wed Jun 30 11:40:26 EST 2010
[INFO] Final Memory: 1M/136M
[INFO] ------------------------------------------------------------------------

I think this rules out it being a problem with the settings.xml or a pom. Is there a way to get more information about why maven cant connect to the repository?

Answer 1

I would guess it has something to do with the repository settings in the pom, a parent pom or in your ~/.m2/settings.xml file. Its also possible that the repo at exoplatform is misconfigured.

With no repositories set the archetype plugin would come from repo1.maven.org

http://repo1.maven.org/maven2/org/apache/maven/plugins/maven-archetype-plugin/

Answer 2

I've tried the same commands and get the same error message, so I've run using the debug flag. This gives a different root exception depending on the proxy settings etc. Try running the same in case you get better verbose output.

mvn -X archetype:generate

Case 1:

Machine not connected to network (Cable disabled) gives a debug message

[DEBUG] Exception
org.apache.maven.wagon.TransferFailedException: Error transferring file
...
Caused by: java.net.UnknownHostException: repo1.maven.org
    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:177)
[INFO] Repository 'central' will be blacklisted

Case 2:

Machine connected with incorrect proxy gives the debug message

[DEBUG] Exception
org.apache.maven.wagon.TransferFailedException: Error transferring file
...
Caused by: java.net.ConnectException: Connection timed out: connect
    at java.net.PlainSocketImpl.socketConnect(Native Method)
[INFO] Repository 'central' will be blacklisted

Case 3:

Machine with direct connection to internet

[DEBUG] Trying repository central
Downloading: http://repo1.maven.org/maven2/org/apache/maven/plugins/maven-archet
ype-plugin/2.0-alpha-5/maven-archetype-plugin-2.0-alpha-5.jar
[DEBUG]   Artifact resolved
[INFO] ------------------------------------------------------------------------

and so on till it works.

Answer 3

Just to close the loop on this one - it turned out to be an issue with the libraries debian had available for java uses to resolve hostnames. The fix is to apply a new libdns for java as described here http://www.ehow.com/how_4747553_fix-unknownhostexception-java-applications-ubuntu.html. Once I did this I am able to run mvn with jdk5 and jdk6.