I try to connect database Mysql in AWS RDS couple of times but somehow when it syncronize System DDL command, it fail. I also took some advices in forum, so I changed runtime port to (like 8888, 5252,...) it result same error messages. the error message in below. Mendix.Modeler.M2EEConnector.M2EEException: The server encountered an error. location : Mendix.Modeler.M2EEConnector.M2EEResponse.CheckSuccess() file C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.M2EEConnector\M2EEResponse.cs:line 57 location : Mendix.Modeler.M2EEConnector.StartupManager.StartRuntime(IM2EEClient client, StartupInfo info) file C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.M2EEConnector\StartupManager.cs:line 119 location : Mendix.Modeler.M2EEConnector.StartupManager.PerformStartup(StartupInfo info, IM2EEClient client) file C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.M2EEConnector\StartupManager.cs:line 53 location : Mendix.Modeler.M2EEConnector.RuntimeController.Start(StartupInfo info, LogLevel autoSubscribeLogLevel) file C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.M2EEConnector\RuntimeController.cs:line 143 location : Mendix.Modeler.Utility.BackgroundUtil.<>c__DisplayClass1_0`1.<Do>b__0(Object s, DoWorkEventArgs e) file C:\Users\Autobuild\workspace\AppStudio4.0-Build\modeler\Mendix.Modeler.Utility\BackgroundUtil.cs:line 29 location : System.ComponentModel.BackgroundWorker.OnDoWork(DoWorkEventArgs e) location : System.ComponentModel.BackgroundWorker.WorkerThreadStart(Object argument)