Errors in software may be detected via the use of design rule spaces and architecture root detection. Design rule spaces may reveal multiple overlapping modular structures of a software system, and reveal structural relations among error-prone files and structural problems contributing to error-proneness. Root detection may extract a few groups of architecturally connected files, which may be connected through problematic architecture relations that propagate errors among these files, and thus influence system error-proneness. The root detector may locate the core architecturally connected file groups that contribute to the error-proneness of a system. The root detection process may, beginning with a set of error-prone files, search and link other files that are architecturally related. The output of the root detection process may be a set of design rule spaces ordered by the number of error-prone contained therein.