Which AI model writes the most bugs in Python?

As of Nov 14, 2026, Grok 4.7 had the highest relative bug rate in Python code (1.36, 36% more counted bugs than the Python average), statistically tied with 4 other models.

Updated Nov 14, 2026

Best AI model for Python code

As of Nov 14, 2026, GPT-6 Luna had the lowest relative bug rate in Python code (0.26, 74% fewer counted bugs than the Python average), among 7 ranked models.

Models ranked by relative bug rate in Python code. Lower values are better.
Rank	Model	Rate
1	GPT-6 Luna	0.26
2	GPT-6.1 Sol	0.53
3= (statistically tied)	Claude Fable 5.1	0.83
4= (statistically tied)	Claude Opus 5.5	1.01
5= (statistically tied)	GPT-6 Astra	1.18
6= (statistically tied)	Claude Sonnet 5.5	1.28
7= (statistically tied)	Grok 4.7	1.36

1.00 = Python average · lower is better · = statistically tied

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Questions and answers

Which AI model writes the most bugs in Python?: As of Nov 14, 2026, Grok 4.7 had the highest relative bug rate in Python code (1.36, 36% more counted bugs than the Python average), statistically tied with 4 other models.