解决办法：

1. Shut down the workspace.

2. Delete  the file com.genuitec.eclipse.ast.deploy.core.prefs which is located at <workspace dir>/.metadata/.plugins/org.eclipse.core.runtime/.settings/com.genuitec.eclipse.ast.deploy.core.prefs3. Start the IDE.

错误：

java.lang.NullPointerException

 at com.genuitec.eclipse.ast.deploy.core.Deployment.<init>(Unknown Source) at com.genuitec.eclipse.ast.deploy.core.ModuleDeployment.<init>(Unknown Source) at com.genuitec.eclipse.ast.deploy.core.WebDeployment.<init>(Unknown Source) at com.genuitec.eclipse.ast.deploy.core.Deployment.create(Unknown Source) at com.genuitec.eclipse.ast.deploy.core.DeploymentManager.loadFromPreferences(Unknown Source) at com.genuitec.eclipse.ast.deploy.core.DeploymentManager.init(Unknown Source) at com.genuitec.eclipse.ast.deploy.core.DeploymentManager.<init>(Unknown Source) at com.genuitec.eclipse.ast.deploy.core.DeploymentManager.getDefault(Unknown Source) at com.genuitec.eclipse.ast.deploy.core.ui.ServerTreeViewer$ServerTreeContentProvider.inputChanged(Unknown Source)