Works locally but fails after deploy
Verdict
When an API integration works locally but fails after deployment, this is often not caused by the request logic itself.
If identical requests succeed in a local environment yet fail once deployed—without code changes—the issue usually lies in execution context, not implementation correctness. Continued refactoring of request code typically yields low returns.
Why This Happens
Deployment changes more than location.
Common structural differences include:
- Network egress paths and outbound filtering
- Runtime identity such as service accounts or instance roles
- Environment-level rate limits or quotas
- Cold starts, concurrency, or resource constraints
These factors alter how and when requests are executed, even if the code is identical.
From the client’s perspective, the API “stopped working.” From the system’s perspective, the execution context changed.
Where You Can Stop
Once you confirm that:
- The same code is running
- Requests are formed and authenticated correctly
- Failures correlate with deployment, not logic changes
You can usually stop:
- Rewriting request construction
- Adding local-only logging to explain remote behavior
- Treating deployment failure as proof of code regression
- Chasing differences that only exist outside the deployed context
Further progress depends on runtime guarantees and environment policies, not client logic.
What This Page Is Not
This page does not:
- Debug deployment pipelines
- Explain hosting or network configuration
- Offer environment parity strategies
Its purpose is to clarify when deployment introduces a new boundary—and when further client-side effort is optional.
Code does not change when deployed. Context does.