Fehlerfall

Fehlerfall is a German term used in engineering and software development to denote a concrete scenario in which a system experiences a fault. A Fehlerfall describes the conditions, inputs, and sequence of events that lead to an error, with the goal of reproducing and analyzing the defect. In software engineering, Fehlerfälle are captured as bug repro scenarios or test cases, including steps to reproduce, expected outcomes, and actual results. They serve to verify defects, guide debugging, and confirm that fixes address the root cause.

In safety- and reliability-oriented contexts, Fehlerfälle form part of risk analysis methods such as failure mode and effects analysis (FMEA) and fault tree analysis. Here they help identify critical fault conditions, assess potential consequences, and design mitigations such as redundancy, exception handling, watchdogs, or safe states. Common sources of Fehlerfälle include unexpected inputs (edge cases), hardware faults, timing and synchronization issues, network outages, and environmental conditions.

Documenting Fehlerfälle supports traceability, testing scope definition, and compliance with standards in industries like automotive, aviation, and medical technology. In practice, a Fehlerfall is not merely a fault name but a defined scenario used throughout the development lifecycle, from isolation of a bug to verification of a safety mechanism. The German term is often used in conjunction with Fehlerfallanalyse to describe the systematic study of such scenarios.