This chapter lists the most common errors that may appear while working with isCOBOL EIS.

If a connection error occurs and the browser cannot load the page with the COBOL application, ensure that Tomcat is correctly started.

Information on Tomcat startup errors can be found in catalina.currentdate.log file in Tomcat's logs directory.

If an empty blank screen appears in place of the COBOL application, it could mean that WD2 could not initialize the program correctly. Error messages that help troubleshooting the cause of the problem can be found in the stdout_currentdate.log, stderr_currentdate.log and localhost.currentdate.log files in Tomcat's logs directory.

"Missing License" is a common problem that causes blank screen. Check that the iscobol.eis.license.2019 property is set in /etc/iscobol.properties or in the web application's WEB-INF/classes/iscobol.properties file.

The blank page may also be caused by the application waiting for Debugger, if iscobol.rundebug property is set in the configuration.

Also, the blank page may be caused by the web application terminating before the first DISPLAY, for example due to i/o errors. Remote debugging can help in this case.

When an error occurs in the web application, it usually causes HTTP ERRORS like 404 and 500.

In order to retrieve the full Exception stack, consult the log files in Tomcat's logs directory.

It can happen that a COBOL program performs a DISPLAY or ACCEPT on the user interface in a EIS environment. This could happen, for example, if you reuse existing code that was previously used in a Desktop environment. These operations are not supported by Servlets and Web Services and may lead to unexpected behaviors and errors. In order to prevent these error conditions, Veryant recommends to add -whttp to your compiler options when you compile programs for the EIS environment.