Intermittent API 500 errors during background agent execution

Description

Experiencing frequent intermittent 500 Internal Server Errors when running background agents via Claude Code CLI. Multiple occurrences during a single session (2026-02-25), affecting agent task execution.

Request IDs

• req_011CYV8QmhU7UFPnHDZ4WHTY
• req_011CYV8URkmx4XZ5Ppzzxre2
• req_011CYV8YwnAjfpmvu4k86UiK
• req_011CYV9chhKZqQzx4qCxQwrA
• req_011CYV9w3xDn4nJjjbYL5ZZP
• req_011CYVAfLw6t9VeQqNroHPw9
• req_011CYVAeCxrGK9dCAz16tpaM

Error Response

{"type":"error","error":{"type":"api_error","message":"Internal server error"}}

Context

• Model: claude-opus-4-6
• Using Task tool with background agents (run_in_background: true)
• Agents performing file reads and edits on a ~1900 line markdown file
• Errors are intermittent — same task succeeds on retry
• 7 failures across ~15 agent launches in one session (~47% failure rate)
• No pattern to which agent types fail (general-purpose, Bash, Explore all affected)

Environment

• macOS (Darwin 25.3.0)
• Claude Code CLI
• Date: 2026-02-25

Impact

Work proceeds but requires manual detection of failures and re-launching agents. No automatic retry mechanism exists, so each failure requires user/orchestrator intervention.