Use the Error Logs command to display and choose Web  to view web runtime error logs:

The Web Runtime Error Log Viewer is designed to help you to locate fatal errors in your code when you are developing web-related applications.

The left pane lists the latest errors sorted by date and time, and the right pane shows details for the error selected in the left pain.

Update the viewer with the latest error messages - if there are any that have not yet reached the list.

This icon opens the actual Web Runtime Error Log file in text format, if that is the one you are accustomed to using.

Press this icon to delete the message that is highlighted in the Details pane or to delete all the messages listed.

Two options available:
Data/application Server: This is where the LANSA application runs. Look here for application errors.
Web server: Process requests from user agents (browsers). Look here for problems connecting to the Data/application server or XSL transformations (when transforming on the web server).

 You can keep this modeless dialog open when you are developing.
⇑ 5.8 Fatal Errors