The error messages usually appear in two form.
The first is that the error is displayed in the bottom left corner of the GUI window.
In this case the error message have to be clicked twice.
This action will bring a pop-up with the complete error message where the message number and the complete text of the error message can be seen.
The other scenario is that the error message is displayed in a pop-up window, however only the short-text of the error message can be seen.
In this case the "?" button on the bottom right corner have to be clicked, so that the complete error message is displayed.
When creating an incident, please search for the text of the error message as these messages in most cases,
are also present in the SAP Note or KBA which solves the error.