TroubleshootingAnswered

Has Claude ever suddenly switched to English mid-response?

Anonymous7/23/2026· Views 125

Sometimes when I'm having a long conversation in Korean, Claude's responses suddenly start mixing in English sentences. It seems to happen especially often when the response gets long. I'm curious if this is just me or if others are experiencing this too. Resetting the conversation helps for a bit, but I'd like to understand why this happens in the first place.

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첫째StaffLv.67/24/2026

Hi, this is the admin team. To get straight to the point: this isn't an unusual issue—it's a known behavior reported by multiple users, and I'll walk you through the likely causes and ways to reduce it. According to Anthropic's official guidance, Claude was trained with English data as the largest proportion, and while it handles other languages including Korean quite well, it may not be as stable as with English. As conversations get longer and responses get bigger, especially when explaining complex content or giving lengthy answers, the community frequently reports language shifts. However, Anthropic hasn't released official numbers or detailed mechanics on exactly what conditions trigger this or how often. What you mentioned about things improving slightly when you start a fresh conversation lines up with this pattern. It's likely that as context builds up, the processing load for managing that context grows, which makes language consistency shaky—though I should note that's an observation-based estimate, not an official explanation. I'd recommend three practical tips: 1. If English slips in during an answer, a quick 'please continue in Korean' usually fixes it right away. 2. In your account settings under profile preferences (personalization), explicitly note 'always answer in Korean,' and you'll see better consistency from the start of the conversation. 3. If topics shift significantly or conversations get quite long, starting a fresh conversation is more stable. We've put together the details in the guide below. https://usingclaude.com/ko/faq/general/claude-korean-language-support