# OpenAI updates GPT-5.6 Sol, cuts factual errors, frees Luna

> OpenAI updated GPT-5.6 Sol and made GPT-5.6 Luna free and unlimited.

*A chat-only refresh merges fast and reasoning modes and makes unlimited GPT-5.6 Luna free for all users.*

By Behzad Hosseini · FeaturedDaily
Canonical: https://featureddaily.com/news/openai-updates-gpt-5-6-sol-cuts-factual-errors-frees-luna

**What happened:** OpenAI released an updated GPT-5.6 Sol in ChatGPT on 6 August 2026, tuned for shorter, more direct answers that correct users rather than simply agreeing with them.

**The numbers:** In OpenAI's own tests on financial, medical and legal prompts, responses containing at least one factual error were 68% less common with GPT-5.6 Sol and about 62% less common with GPT-5.6 Luna, compared with GPT-5.5 Instant. OpenAI credits better use of the sources it looks up.

**The catch:** This is OpenAI's own testing, not an independent benchmark. The update is chat-only: Sol in ChatGPT Work and Codex is unchanged, and this is still GPT-5.6, not a new model generation.

**Who's affected:** Plus and Pro users get a single Sol model that now covers both quick answers and deep reasoning, controlled by a slider. Free and Go users get a new "Think" button instead.

**The details:** Free and Go users also now get GPT-5.6 Luna as their default model, with unlimited text chats rolling out from 7 August.

**Why it matters:** Anthropic currently leads business spending on AI. OpenAI is betting on better answer quality and wider free access to hold onto its consumer lead.

**The context:** Protections for under-18s were also strengthened, including new limits on romantic role-play.

**What's next:** OpenAI moved the model picker into settings, a change some users have already criticised on X. [More detail from DataNorth](https://datanorth.ai/news/openai-updates-gpt-5-6-sol-and-gpt-5-6-luna).

## Key takeaways

- GPT-5.6 Sol update cuts factual-error responses by 68% in OpenAI's own tests
- Sol now merges fast and reasoning modes with a slider for Plus and Pro users
- GPT-5.6 Luna becomes free and unlimited for text chats from 7 August

## Sources

- [OpenAI updates GPT-5.6 Sol in ChatGPT, Luna goes free](https://datanorth.ai/news/openai-updates-gpt-5-6-sol-and-gpt-5-6-luna) — DataNorth, 2026-08-07