Where code execution results in an error attributable to multiple data elements, the code is revised so the error results from one element. Where execution improperly functions without error, and the elements contain required but missing properties, the code is improperly functioning in its required-property handling. Errors are organized into classes and error-causing elements are organized into independent sets corresponding to the classes. Elements that are not within any set are determined. Symptom, error, no-error, refined-symptom, and function databases can be employed during code execution analysis. Symptom database entries correspond to elements and indicate errors, or that no errors, are attributable to the elements. Error database entries correspond to elements resulting in errors upon execution. No-error database entries correspond to elements resulting in no errors upon execution. Refined-symptom database entries correspond to root cause elements of errors. Function database entries correspond to root cause elements of no errors.