OpenAI SDK Non-Streaming Calls Hang Indefinitely Behind NAT Due to Missing TCP Keepalive

What this error means

Non-streaming OpenAI API calls silently hang forever behind NAT — default httpx transport has no TCP keepalive is a OpenAI API failure pattern reported for developers trying to fix indefinite hanging on long openai api calls caused by nat gateway idle timeout dropping tcp connections without keepalive. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Open issue #3269 on openai/openai-python (created May 19, 2026, labeled ‘bug’). The default httpx transport has SO_KEEPALIVE off. During long non-streaming calls, NAT gateways silently drop idle TCP connections while server generates response — user never receives it. Affected: Responses API with reasoning models and completions.create(). This is a production-breaking bug affecting paying users with enterprise infra.

Common causes

• Open issue #3269 on openai/openai-python (created May 19, 2026, labeled ‘bug’). The default httpx transport has SO_KEEPALIVE off. During long non-streaming calls, NAT gateways silently drop idle TCP connections while server generates response — user never receives it. Affected: Responses API with reasoning models and completions.create(). This is a production-breaking bug affecting paying users with enterprise infra.

Quick fixes

1. Confirm the exact error signature matches Non-streaming OpenAI API calls silently hang forever behind NAT — default httpx transport has no TCP keepalive.
2. Check the OpenAI API 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/openai/openai-python/issues/3269

Evidence note: Open issue #3269 on openai/openai-python (created May 19, 2026, labeled ‘bug’). The default httpx transport has SO_KEEPALIVE off. During long non-streaming calls, NAT gateways silently drop idle TCP connections while server generates response — user never receives it. Affected: Responses API with reasoning models and completions.create(). This is a production-breaking bug affecting paying users with enterprise infra.

Related errors

• OpenAI API

FAQ

What should I check first?

Start with the exact Non-streaming OpenAI API calls silently hang forever behind NAT — default httpx transport has no TCP keepalive text and the smallest action that reproduces it.

Can I ignore this error?

No. Treat it as a failed OpenAI API 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 Non-streaming OpenAI API calls silently hang forever behind NAT — default httpx transport has no TCP keepalive.