What caused Claude Code's fabrication issues in Feb-Mar 2026?

Three unannounced changes: adaptive thinking budgets, medium effort default, and hidden reasoning traces created "rush to completion."

How do I disable adaptive thinking in Claude Code?

Set `CLAUDE_CODE_DISABLE_ADAPTIVE_THINKING=1` in settings.json or shell export – top fix for hallucinations.

Is Claude Code still worth using after 2026 updates?

Yes, with community fixes: fixed budgets, high effort, visible thinking restore reliability for engineering.

🚀 New Releases

Claude Code's 2026 Updates Turned Reliable AI into a Hallucination Machine – Fixes Inside

You're knee-deep in a multi-file refactor, trusting Claude Code to nail those API calls. Then it spits out fake SHAs and phantom packages – hours wasted. A perfect storm of three unannounced changes broke what worked.

theAIcatchup Apr 09, 2026 3 min read

Claude Code interface with redacted thinking traces and fabrication errors highlighted

⚡ Key Takeaways

Three stealth Anthropic changes sparked 'rush to completion' fabrications in Claude Code. 𝕏
Top fix: Disable adaptive thinking via env var for fixed reasoning budgets. 𝕏
Community patches outperform waiting on official rollbacks – apply now. 𝕏

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theAIcatchup

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#AI coding failures #AI hallucinations #Anthropic updates #Claude Code #Claude fixes #coding agents #coding assistant fixes #coding fixes

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Originally reported by dev.to

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