Error message (Wikipedia)
Wikipedia’s article on error messages: a short text description of a problematic situation, distinguished from warnings (potential, not actual, problems) and from purely informational messages, and distinguished from raw error data (a core dump or stack trace is error information but not itself an “error message”). Covers presentation techniques (modal dialog, OS-level notification icon, status bar), the three factors that shape message content (display/technical constraints, the error’s complexity, and security), a glossary of common system-level error conditions, a list of notable/notorious specific error messages, and “Fail Pets” (whimsical error mascots as a Web 2.0-era branding pattern).
License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/
Key points
- Error messages must not leak exploitable information. The canonical bad example: a login form that shows “invalid username” or “invalid password” depending on which field was wrong — this confirms to an attacker which usernames are valid, narrowing a credential-stuffing attack. A single generic message (“invalid username or password”) avoids that leak. A second historical example: IIS 5.0’s default error page once displayed a complete technical error description including a source-code fragment.
- Message content should scale to both the error’s real complexity and the display’s real constraints — a terse hardware display (e.g. a 16-character printer readout) forces brevity regardless of how much the underlying problem actually warrants explaining; a complex failure genuinely needs more explanation than a simple one.
- HP’s “PC LOAD LETTER” is cited as the canonical example of a confusing, jargon-heavy error message: asking users to load “Letter”-size paper in wording that doesn’t read as an instruction at all.
- Fail Pets / Error Mascots: with the rise of Web 2.0 services, user-facing error pages (HTTP 404, 500, service outages) started using whimsical illustrated characters instead of bare technical text — Twitter’s Fail Whale, GitHub’s Octocat, Google’s broken robot, Tumblr’s “Tumbeasts.” Design researcher Sean Rintel frames this as a real branding trade-off: a distinctive failure illustration builds recognition (often via earned media when people share it), but that same memorability means it’s tied to highlighting the failure itself.