Writing usable error messages

HowTo: Write A Usable error message

Writing error messages is hard, but critical to the usability of a system.

Good error messages result in the users being able to fix their problem in seconds. Bad ones can distract your user for hours.

An error message should consist of three parts:

1. What happened
2. Why is that an error (if not obvious)
3. What the user can do next (if known)

Additionally:

• An error summary that can be used to display when there is reduced screen space available.
• Detailed diagnostics

Aim for terse, accurate information. If in doubt about the accuracy of the data, show the user less not more, otherwise you risk distracting them down the wrong path.