"Updating Maven Project". Unsupported IClasspathEntry kind=4

The problem is caused by the fact that STS (the Spring IDE/Eclipse), as well Eclipse and other Eclipse based IDE's, use the m2e(clipse) plugin but that eclipse:eclipse has been probably been run on the project. When m2e encounters a "var" .classpath entry, it throws this error.
In order to fix this problem, you need to do the following:
Make sure that the version of the m2e(clipse) plugin that you're running is at least 1.1.0, and preferably, the latest available. The update site is the following url: http://eclipse.org/m2e/download/.
Disable the maven nature for the project (via the right-click menu)
run mvn eclipse:clean (while your project is open in STS/eclipse)
re-enable the maven nature.(Most of the time, this can be done by right-clicking on the project in question in the package explorer pane, and then choosing 'Configure'-> 'Convert to Maven Project')
问题解决：

1.确定m2e插件的版本》1.1.0；

2.右键，设置“disable the maven nature”；

3. 运行 mvn eclipse：clean命令；

4.右键-》configure-》convert to maven project。