Claude change history: Elevated errors for Claude Opus 5.5

Claude reported a major incident involving elevated errors for Claude Opus 5.5 across claude.ai, Claude API (api.anthropic.com), Claude Code, and Claude Cowork. It started at 2026-10-06 12:24 UTC and was resolved at 2026-10-06 12:43 UTC, lasting 18 min. Claude said it identified the cause but did not disclose the cause or fix.