In order for an error message to be useful to the user who encounters it, it should convey the following information:
- that an error has occurred;
- what the error is;
- how users can correct or get around the error;
- where users can get more information about the error.
In the text of the error message, use the same terminology to which the user is accustomed. Consistently call all items by the same names they are called in the GUI.
Use the active voice, not the passive voice.
Here’s an example:
|BAD||BETTER||EVEN BETTER||WHAT THE USER|
|IP unreachable. A reachable network must be used.||You must specify a reachable network.||The specified IP address is unreachable.||Check that you are connected to the network.|