An unknown error occurred while starting the server.
Mendix.Modeler.M2EEConnector.M2EEException: The server encountered an error.
at Mendix.Modeler.M2EEConnector.M2EEResponse.CheckSuccess() in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.M2EEConnector\M2EEResponse.cs:line 57
at Mendix.Modeler.M2EEConnector.StartupManager.PerformStartup(StartupInfo info, IM2EEClient client) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.M2EEConnector\StartupManager.cs:line 32
at Mendix.Modeler.M2EEConnector.RuntimeController.Start(StartupInfo info, LogLevel autoSubscribeLogLevel) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.M2EEConnector\RuntimeController.cs:line 134
at Mendix.Modeler.Utility.BackgroundUtil.<>c__DisplayClass1_0`1.<Do>b__0(Object s, DoWorkEventArgs e) in C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Utility\BackgroundUtil.cs:line 29
at System.ComponentModel.BackgroundWorker.OnDoWork(DoWorkEventArgs e)
at System.ComponentModel.BackgroundWorker.WorkerThreadStart(Object argument)
检查一下 project module 中的的setting的database设置是否正确。 运行一个空项目检查是否出现这种错误，若出现，检查jdk环境是否是编译问题。
运行一个空项目依旧报错，感觉JDK环境
也没问题啊。
8080端口被占用
在项目Settings/Server选项卡里面改端口号