Your server most likely writes its log files, not to System.out or System.err. Where they are located will depend on your server. For example, Tomcat logs will be in <tomcatInstallDir>/logs. The Ultimate version, which has server startup configurations, will automatically open these logs (for most server types). In Community Edition, you will need to find where these logs are located, and then configure IDEA to automatically display them when the application starts.
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