A crash loop is a repeated failure cycle in which a system starts, hits a fatal error, restarts, and then fails again before it can reach normal use. The loop may happen during boot, when a service loads, or after an update changes a critical component. In Windows environments, it often shows up as repeated blue-screen reboots or a machine that never reaches the desktop.
Crash loops matter because they can lock users out of the device and block the very tools needed to repair it. In security work, they may be triggered by a bad driver, a faulty remediation package, or a conflict in a privileged recovery path. Attackers can also aim for this outcome to create denial of service, while defenders look for version tracking, rollback options, and safe recovery modes to break the loop.