Claude Code Hanging on Thinking Prompts After Opus 4.6

What this error means

Claude Code hangs/freezes on 'thinking' for 5-20+ minutes; SSE events not received from Anthropic endpoint is a Claude Code failure pattern reported for developers trying to fix claude code freezing or getting stuck on thinking prompts for extended periods. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

GitHub issue #26224 (100 comments) reports Claude Code stuck ‘thinking’ for 5-20+ minutes with no token usage. Packet inspection confirms SSE events are not being received from Anthropic endpoint. Triggered since Opus 4.6 release.

Common causes

• Since Opus 4.6 release, Claude Code frequently hangs for 5-20 minutes on prompts with no token usage increase. Packet inspection shows SSE events are not arriving from Anthropic. Affects large number of paid users (100+ comments).
• GitHub issue #26224 (100 comments) reports Claude Code stuck ‘thinking’ for 5-20+ minutes with no token usage. Packet inspection confirms SSE events are not being received from Anthropic endpoint. Triggered since Opus 4.6 release.

Quick fixes

1. Confirm the exact error signature matches Claude Code hangs/freezes on 'thinking' for 5-20+ minutes; SSE events not received from Anthropic endpoint.
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/26224

Evidence note: GitHub issue #26224 (100 comments) reports Claude Code stuck ‘thinking’ for 5-20+ minutes with no token usage. Packet inspection confirms SSE events are not being received from Anthropic endpoint. Triggered since Opus 4.6 release.

Related errors

• Claude Code SSE connection timeout
• Claude Code Opus 4.6 performance regression
• Anthropic API streaming timeout errors

FAQ

What should I check first?

Start with the exact Claude Code hangs/freezes on 'thinking' for 5-20+ minutes; SSE events not received from Anthropic endpoint 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 Claude Code hangs/freezes on 'thinking' for 5-20+ minutes; SSE events not received from Anthropic endpoint.