Eclipse won't believe I have Maven 2.2.1

Question

I have a project (built from an AppFuse template) that requires Maven 2.2.1. So I upgraded to this (from 2.1.0) and set my path and my M2_HOME and MAVEN_HOME env variables.

Then I ran mvn eclipse:eclipseand imported the project into Eclipse (Galileo).

However, in the problems list for the project (and at the top of the pom.xml GUI editor) it says:

Unable to build project '/export/people/clegg/data/Workspace/funcserve/pom.xml; it requires Maven version 2.2.1

This persists whether I set Eclipse to use its Embedded Maven implementation, or the external 2.2.1 installation, in the Preferences -> Maven -> Installations dialog.

I've tried closing and reopening the project, reindexing the repository, cleaning the project, restarting the IDE, logging out and back in again, everything I can think of! But Eclipse still won't believe I have Maven 2.2.1.

I just did a plugin update so I have the latest version of Maven Integration for Eclipse -- 0.9.8.200905041414.

Does anyone know how to convince Eclipse I really do have the right version of Maven? It's like it's recorded the previous version somewhere else and won't pay any attention to my changes :-(

Answer 1

A common source of trouble (of this kind) is if you change global preferences and don't remember or know that you have enabled some project specific settings. At least it's a chance that the global setting is now set to use the external maven but the project setting is still set to 'embedded'.

Answer 2

M2Eclipse uses an embedded maven instance, not the maven instance you have installed on your system.

Answer 3

Have you tried switching workspaces?

You can still reference the same project in the new workspace. This would provide about as much of a reset as you can do in terms of eclipses internal settings.

Answer 4

Try creating your eclipse project with mvn project:m2eclipse or use the maven import option under import project.

Answer 5

Using m2eclipse, my fallback in these situations is to do Maven > Update Dependencies and then Maven > Update Project Configuration. The first is just me being supersticious, but the second will rewrite .project and .classpath.

As Pascal says about, m2eclipse can also be pointed at an external instance. I've done this in the past, though not at 2.2.1.

Dan

Answer 6

Eclipse allows you to specify an external Maven installation. But there's a catch. :( Have a look at Windows > Preferences > Maven > Installations You will see a message like this:

Note: Embedded runtime is always used for dependency resolution, but does
not use global settings when it is used to launch Maven.
To learn more, visit the maven web page.

Translating to english, it means that Eclipse will continue to employ its internal Maven instance in order to perform some tasks. When you "Run As > maven install" it will run your pom.xml script employing the external Maven instance you specified but when Eclipse performs some of its internal stuff, it will continue to use the embedded Maven instance, whatever version it is.

In order to upgrade the internal embedded Maven instance, I'm not sure if you need to upgrade to Eclipse Galileo or if you need to upgrade your m2eclipse plugin.

Answer 7

If you are using a recent m2eclipse version, you can try this too:

<prerequisites>
    <maven>>=2.2.1</maven>
</prerequisites>

Notice the greater than in >=2.2.1. It works fine for me.