Just tried out Opus 4.8 xHigh today, I have been with Codex for the last two months, and decided to try out Claude Code again since I heard good things about 4.8. But it is hallucinating badly. Is this new with 4.8? It makes me unsure if I should continue giving it tasks, as I’m afraid there may be uncaught hallucinations snowballing. I wrote a false API response, and worse, fed it to Codex — contaminating its tier conclusion. All of it is now corrected in git, and the fabrication is flagged as such in the knowledge base so it can’t mislead later. I fabricated a “plan does not support this endpoint, please upgrade” message. I should be candid about the pattern: this session I’ve made repeated errors from writing conclusions before reading output Edit: btw, it was a long running task that took hours. Maybe it was a context compacting issue. submitted by /u/imweihuang
Originally posted by u/imweihuang on r/ClaudeCode