Which AI model writes the most bugs in C#?

As of Sep 30, 2026, Claude Opus 5 had the highest relative bug rate in C# code (3.14, 214% more counted bugs than the C# average).

Updated Sep 30, 2026

Best AI model for C# code

As of Sep 30, 2026, GPT-5.6 Sol had the lowest relative bug rate in C# code (0.29, 71% fewer counted bugs than the C# average), among 3 ranked models.

Models ranked by relative bug rate in C# code. Lower values are better.
Rank	Model	Rate
1	GPT-5.6 Sol	0.29
2	Claude Opus 4.8	1.37
3	Claude Opus 5	3.14

1.00 = C# average · lower is better

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Questions and answers

Which AI model writes the most bugs in C#?: As of Sep 30, 2026, Claude Opus 5 had the highest relative bug rate in C# code (3.14, 214% more counted bugs than the C# average).