Warning and Error Messages
A good warning or error message contains two elements:
- A brief description of the problem.
- A list of ways the user can remedy the problem.
Both of these elements should be presented in non-technical, jargon-free language, unless your target audience is particularly technically-minded.
If your application knows enough about the problem to be able to give all this information to the user, it will often be capable of rectifying the problem itself when the user has decided which course of action they want to take. For example, if the problem is insufficient memory, tell the user which currently-running application is taking up the most memory, and provide a button to close it for them. (Do not offer to launch a graphical process manager, however, which is something most users should never see!)
See Section 3.4 ― Alerts for more detailed information on writing and presenting errors, warnings and information alerts.