Skip to content
Free public beta until December 4, 2026: every course is open, no card needed. After that, the first chapter of each course stays free and full access is a one-time $39 ($19 for up to 100 founding members chosen for helpful feedback). Your progress is kept. How the beta works

exception filter

An extra condition on a catch, written with when, that must be true to catch.

A catch clause's when (condition) is evaluated before the stack unwinds; if it is false the exception keeps propagating as if that clause did not exist.

Loading interactive…

Examples

  • catch (HttpRequestException ex) when (ex.StatusCode == HttpStatusCode.NotFound) catches only a 404 and lets every other failure keep travelling.

See also

try/catch exception
Read the full section →