Claude Code /goal Stop Hook JSON Validation Failed — Fix Goal Auto-Clear

What this error means

Stop hook error: JSON validation failed is a Claude Code failure pattern reported for developers trying to fix claude code /goal stop hook failing with json validation error preventing auto-goal clearance. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

GitHub issue #58558 filed 2026-05-13 documents the /goal Stop hook rejecting markdown-fenced JSON output. The hook runs Claude as subprocess, which outputs JSON in code fences. Validator rejects it despite structurally valid JSON. Results in: (1) error shown every turn, (2) goal never auto-cleared, (3) requires manual /goal clear.

Common causes

• The /goal feature’s Stop hook rejects valid JSON output wrapped in markdown code fences, showing ‘Stop hook error: JSON validation failed’ every turn end. Goals never auto-clear, forcing manual /goal clear commands. This breaks the documented auto-complete workflow for task-oriented sessions.
• GitHub issue #58558 filed 2026-05-13 documents the /goal Stop hook rejecting markdown-fenced JSON output. The hook runs Claude as subprocess, which outputs JSON in code fences. Validator rejects it despite structurally valid JSON. Results in: (1) error shown every turn, (2) goal never auto-cleared, (3) requires manual /goal clear.

Quick fixes

1. Confirm the exact error signature matches Stop hook error: JSON validation failed.
2. Check the Claude Code account, local tool state, and provider configuration involved in the failing workflow.
3. Compare the failing environment with a known working setup, then change one configuration value at a time.

Platform/tool-specific checks

• Verify the command, editor, extension, or API client that produced the error.
• Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
• Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

1. Capture the exact error message and the command, editor action, or request that triggered it.
2. Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
3. Review the source evidence below and compare it with your environment.
4. Apply one change at a time and rerun the smallest failing action.
5. Keep the working fix documented for the team or deployment environment.

How to prevent it

• Keep provider/tool configuration documented.
• Record non-secret diagnostics such as tool version, provider name, model name, and command path.
• Add a lightweight check before CI or production workflows depend on the tool.

Sources checked

• https://github.com/anthropics/claude-code/issues/58558

Evidence note: GitHub issue #58558 filed 2026-05-13 documents the /goal Stop hook rejecting markdown-fenced JSON output. The hook runs Claude as subprocess, which outputs JSON in code fences. Validator rejects it despite structurally valid JSON. Results in: (1) error shown every turn, (2) goal never auto-cleared, (3) requires manual /goal clear.

Related errors

• Claude Code /goal not clearing automatically
• Claude Code hook JSON parse error
• Claude Code stop hook exit code 1

FAQ

What should I check first?

Start with the exact Stop hook error: JSON validation failed text and the smallest action that reproduces it.

Can I ignore this error?

No. Treat it as a failed Claude Code workflow until the root cause is understood.

Is this guaranteed to have one fix?

No. The imported evidence supports the troubleshooting path above, but tool behavior can vary by account, plan, version, provider, and local configuration.

How do I know the fix worked?

Rerun the same command, editor action, or request. The fix is working when that action completes without Stop hook error: JSON validation failed.