Why are requests failing on my inference server?

There are a lot of possible causes, but the fastest way to narrow it down is to check what kind of failure you’re seeing:

Common reasons inference requests fail

1) Model/server isn’t actually ready

• Model still loading
• Warmup not finished
• Container started but health checks failing

Check: server logs for load/warmup errors, and health endpoint status.

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2) Input format mismatch

• Wrong JSON schema
• Missing required fields
• Incorrect tensor shape / dtype
• Bad image/audio/text encoding

Check: compare your request payload to the server’s expected schema.

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3) Payload too large

• Request body exceeds max size
• Large images/audio/video causing timeouts or memory issues

Check: API gateway / proxy limits, server max request size, and request logs.

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4) Timeout or cold start latency

• First request after scale-up takes too long
• Model inference exceeds client/server timeout
• Proxy/load balancer timeout shorter than inference time

Check: compare client timeout, gateway timeout, and inference duration.

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5) Resource exhaustion

• GPU/CPU/RAM OOM
• Too many concurrent requests
• Queue backlog or thread pool saturation

Check: metrics for memory, GPU utilization, request queue depth, and logs for OOM errors.

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6) Networking / routing issues

• DNS failures
• Wrong endpoint or port
• TLS/certificate issues
• Load balancer misconfiguration

Check: can you curl the endpoint directly? Any 4xx/5xx status codes?

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7) Authentication / authorization

• Expired API key or token
• Missing headers
• Incorrect tenant/project/model permissions

Check: 401/403 responses and auth logs.

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8) Server-side application errors

• Exception in preprocessing/postprocessing
• Bug in model wrapper
• Unsupported input edge case

Check: application logs and stack traces.

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What I need from you to diagnose it

Please paste any of these:

1. Exact error message or HTTP status code
2. A sample request payload (redact secrets)
3. Inference server logs around the failure
4. Which server/framework you’re using (vLLM, Triton, TensorRT-LLM, TorchServe, FastAPI, etc.)
5. Whether it fails for:
   • all requests or only some
   • only first request
   • only large inputs
   • only concurrent traffic

Quick triage

If you want, send:

• the request you’re making
• the response/error
• the last ~30 lines of server logs

and I’ll help you pinpoint the cause.