启动eclipse时maven插件报错，并且不能编译了。
错误信息：
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 (525).
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 (525).
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 (525).
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 (525).
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 (525).
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 (525).
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 (525).
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 (525).
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 (525).
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 (525).
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 (525).
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 (525).
求解！
我也遇到这样的问题了，不知道楼主最后解决了吗
一般遇到maven的问题就干两件事情
1. mvn clean
2. mvn install
你看看能不能行
解决方案：
删除该工作空间所有maven projects，重启eclipse。再重新导入maven projects。原因：
可能由于意外退出eclipse，导致无法启动maven插件。