A research team led by members from The University of Osaka helps develop a new method to pinpoint code changes that introduce software bugs

Osaka, Japan – We all know how frustrating software bugs can be. But finding the exact line of code that caused a bug can be even more frustrating for developers, especially when thousands of changes have been made to the code over time.

The good news is that researchers are working on a solution. In a new article published in IEEE Transactions on Software Engineering, a collaborative team from The University of Osaka, Kyushu University, and the University of Victoria has created a new method called Majority Voting SZZ (MV-SZZ) that helps developers accurately identify the exact code change that introduced a bug.

Software bugs are unavoidable, and fixing these mistakes can take a lot of time and money, particularly in large projects with many contributors. To help with this, developers use the SZZ method, which takes a bug fix and traces the code history to identify the change that likely caused the problem. But the SZZ method is far from perfect.

“The idea behind the original SZZ method is to examine lines of code in their entirety,” says lead author Inase Kondo. “As a result, it can miss small edits or incorrectly blame changes that have nothing to do with the bug.”

Other variations of the SZZ method attempt to improve accuracy by breaking lines of code into smaller pieces, similar to analyzing individual words instead of full sentences. This can help uncover hidden bug sources but can also create confusion by flagging too many changes as possible causes. The MV-SZZ method solves this problem by grouping these smaller pieces together and using a “majority vote” to decide which change is most likely responsible.

“The MV-SZZ method strikes a delicate balance between coarse and fine,” explains senior author Yoshiki Higo. “By combining detailed change tracking with a majority voting mechanism, we are able to significantly lower the false positive rate.”

When the research team compared their method with six existing approaches, they found that MV-SZZ performed the best overall: it found the real sources of bugs very accurately while reducing incorrect matches.

“Even small improvements in accuracy can save developers a lot of time and effort,” says Kondo. “Our results show that majority voting is a simple yet effective way to improve defect tracking.”

By making it easier to find where bugs begin, this research could help developers build more reliable and cost-effective software, leading to smoother apps, safer systems, and most importantly, fewer frustrating glitches for users.
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The article, “MV-SZZ: A Majority Voting-Based SZZ Method,” was published in IEEE Transactions on Software Engineering at https://doi.ieeecomputersociety.org/10.1109/TSE.2026.3688089

About The University of Osaka
The University of Osaka was founded in 1931 as one of the seven imperial universities of Japan and is now one of Japan's leading comprehensive universities with a broad disciplinary spectrum. This strength is coupled with a singular drive for innovation that extends throughout the scientific process, from fundamental research to the creation of applied technology with positive economic impacts. Its commitment to innovation has been recognized in Japan and around the world. Now, The University of Osaka is leveraging its role as a Designated National University Corporation selected by the Ministry of Education, Culture, Sports, Science and Technology to contribute to innovation for human welfare, sustainable development of society, and social transformation.
Website: https://resou.osaka-u.ac.jp/en