GPT-5.6 Luna Becomes the Free DefaultGPT-5.6 Luna will replace GPT-5.5 as the default model for Free and Go users starting this week. Plus and Pro Get an Updated GPT-5.6 SolChatGPT Plus and Pro users are receiving an updated version of GPT-5.6 Sol designed specifically for everyday conversations. In OpenAI’s internal evaluation, responses containing factual errors were 68% less common with GPT-5.6 Sol than with GPT-5.5 Instant. Work and Codex Models Remain UnchangedThe updated GPT-5.6 Sol is specifically optimized for the standard ChatGPT experience. GPT-5.6 Luna will become the default for Free and Go users during the week, followed by unlimited text chats and the Think button next week.