A Range Error, such as the pictured Array Range Check Error, can appear anywhere, even on Server. Simply click Continue to keep working. The point, though, is to find anomalies and fix them, so please report these to firstname.lastname@example.org.
This Solution provides more details. (6888)
Range Errors are the result of more stringent error checking. The point is to find anomalies and fix them. In the pictured example, Server is sending a Note to a user using the common code for Notes. At the step to "show" that it is saving, it gets an error (there is no Note window to show this message on because it's running on the server). This is harmless and perfectly okay to click Continue on. However, it is exactly the sort of small error we would like to find and fix in case it leads to a bigger error. As you know, if you let us know we can connect, with your help, diagnose, and fix.