[Maven] Error instantiating builder ‘org.eclipse.m2e.core.maven2Builder’.

Problem
My eclipse had shut down unexpectedly. As I restart eclipse, and try to do maven clean.

The console show this error message

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Errors occurred during the build. Error instantiating builder ‘org.eclipse.m2e.core.maven2Builder’. Plug-in org.eclipse.m2e.core was unable to load class org.eclipse.m2e.core.internal.builder.MavenBuilder. An error occurred while automatically activating bundle org.eclipse.m2e.core (524).

Solution
Step 1. Shut down eclipse
Step 2. execute eclipse with -clean parameter, i.e. "eclipse.exe -clean"
Then the Maven is working fine.

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[INFO] Scanning for projects... [INFO] [INFO] ------------------------------------------------------------------------ [INFO] Building FMS :: Entity Classes 1.0.0-SNAPSHOT [INFO] ------------------------------------------------------------------------ [INFO] [INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ fms-entity --- [INFO] Deleting D:\git\fms\fms-entity\target [INFO] ------------------------------------------------------------------------ [INFO] BUILD SUCCESS [INFO] ------------------------------------------------------------------------ [INFO] Total time: 1.229s [INFO] Finished at: Mon May 04 17:42:59 CST 2015 [INFO] Final Memory: 5M/120M [INFO] ------------------------------------------------------------------------

Reference
[1] http://stackoverflow.com/questions/25929458/building-workspace-has-encountered-an-error