What does EventHub metric "Server Errors" means and how to troubleshoot when it happens?

Hi Yuanbo Lin

Thanks for sharing the additional details this is helpful.

If you are seeing System.TimeoutException or System.OperationCanceledException from EventHubBufferedProducerClient.SendEventBatchFailedAsync (and not ServerBusyException or QuotaExceededException), this typically indicates that the client was unable to complete the send operation within the expected time rather than an explicit throttling response from the service.

In practice, this can still correlate with the Server Errors metric because:

• When the service is under load or approaching limits, requests may take longer to be processed, eventually leading to client-side timeouts.

Transient network latency, AMQP link delays, or connection instability can also cause the operation to be canceled or timed out before completion.

To troubleshoot further, I recommend:

Checking if the issue is intermittent or during peak load, which may indicate throughput pressure.

Reviewing client configuration such as retry policy, tryTimeout, and maximum concurrent sends.

Verifying network conditions (latency, firewall/proxy, SNAT exhaustion if applicable).

Enabling Event Hubs diagnostic logs to confirm if requests are being throttled or delayed on the service side.

As a mitigation, you can:

Increase the client timeout (TryTimeout) and ensure retries use exponential backoff.

Reduce batch size or concurrency temporarily to see if the failures decrease.

Scale up throughput units if the workload is close to capacity.

So while you’re not seeing explicit throttling exceptions, these timeout/cancellation errors are often symptoms of pressure or transient conditions, rather than a direct service fault.