LiteLLM / LiteLLM

LiteLLM Proxy Failover Fails Due to APIConnectionError in cooldown_handlers

Fix LiteLLM proxy failover not working when a deployment host is unreachable Includes evidence for LiteLLM troubleshooting demand.

Source-backed Last updated May 13, 2026 1 source Needs local verification

Category: LiteLLM
Error signature: APIConnectionError
Quick fix: Check the build output, project root, and deployment platform configuration before redeploying.
Updated: May 13, 2026
Verification status: Source-backed
Evidence: 1 public source URL

Before you change production

This page includes public source URLs in the imported troubleshooting record. Compare those references with your version and environment before applying changes.

Reproduce the smallest failing action and save non-secret logs before changing configuration.
Check versions for LiteLLM, related SDKs, package managers, CI runners, and hosting providers.
Change one setting or dependency at a time, then rerun the same failing command or request.
Avoid destructive commands, credential rotation, billing changes, or security relaxations without a rollback plan.

What this error means

APIConnectionError is a LiteLLM failure pattern reported for developers trying to fix litellm proxy failover not working when a deployment host is unreachable. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Bug report (2026-05-07) identifies root cause: cooldown_handlers.py line 57 has hardcoded ignored_strings=['APIConnectionError'], causing _is_cooldown_required() to return False, preventing failover to healthy deployments in the same model group.

Common causes

LiteLLM is a paid proxy/router for multi-model LLM deployments. When failover doesn't work due to hardcoded APIConnectionError exclusion, all requests to dead hosts fail without routing to healthy deployments — causing production outages.
Bug report (2026-05-07) identifies root cause: cooldown_handlers.py line 57 has hardcoded ignored_strings=['APIConnectionError'], causing _is_cooldown_required() to return False, preventing failover to healthy deployments in the same model group.

Quick fixes

Confirm the exact error signature matches APIConnectionError.
Check the LiteLLM account, local tool state, and provider configuration involved in the failing workflow.
Check the build output, project root, and deployment platform configuration before redeploying.

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

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

Diagnostic flow for this page

Match APIConnectionError exactly before applying the quick fix.
Compare the failing environment with LiteLLM versions, account scope, provider settings, and deployment context.
Check the listed common causes in order, starting with the cause that best matches your logs.
Use the evidence status below to decide whether to confirm against public sources or official documentation.
Apply one reversible change, rerun the smallest failing action, and keep rollback notes.

FAQ

What does APIConnectionError mean in LiteLLM?

APIConnectionError indicates the workflow described by "LiteLLM Proxy Failover Fails Due to APIConnectionError in cooldown_handlers" failed in a LiteLLM context. Start by confirming the exact signature and the component that emitted it.

What should I check first for APIConnectionError?

Check whether this cause matches your environment: LiteLLM is a paid proxy/router for multi-model LLM deployments. When failover doesn't work due to hardcoded APIConnectionError exclusion, all requests to dead hosts fail without routing to healthy deployments — causing production outages.

Is the APIConnectionError guidance source-backed?

The "LiteLLM Proxy Failover Fails Due to APIConnectionError in cooldown_handlers" page is labeled source-backed. It has 1 public source URL from github.com, so use that evidence status when deciding how much additional verification you need.

When should I avoid the quick fix for APIConnectionError?

For "LiteLLM Proxy Failover Fails Due to APIConnectionError in cooldown_handlers", avoid applying "Check the build output, project root, and deployment platform configuration before redeploying." when the error text differs, the affected version or provider is different, or the change would touch credentials, billing, DNS, production deploy settings, or irreversible data.

What should I collect before debugging APIConnectionError?

For "LiteLLM Proxy Failover Fails Due to APIConnectionError in cooldown_handlers", collect the failing LiteLLM command or request, non-secret configuration, versions, timestamps, request IDs when available, and the smallest reproduction that still triggers the signature.