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LinuxForWhenItMatters
Oct 08, 2025Copper Contributor
Azure AD Health Failing
I am on the latest version of Azure AD Connect (2.5.79.0)... There are no network/DNS/connectivity issues at our site, it seems to me that Azure AD Health Service is having trouble because the endpoint is experiencing a service issue.. Is anyone else having the same problem with failure alerts/etc?
I checked by running "Test-MicrosoftEntraConnectHealthConnectivity -Role SYNC" command, the stack trace throws an undocumented error number and complains of rate limiting issues... smells like the server is being overwhelmed or there are other issues slowing down the endpoint/service with the consequence that connections are piling up causing this error:
Connectivity Test Step 1 of 2: Testing dependent service endpoints begins ...
AAD CDN connectivity is skipped.
Connecting to endpoint https://login.microsoftonline.com
Endpoint validation for https://login.microsoftonline.com is Successful.
Connecting to endpoint https://s1.adhybridhealth.azure.com/providers/Microsoft.ADHybridHealthService/diagnostics/version
Endpoint validation for https://s1.adhybridhealth.azure.com/providers/Microsoft.ADHybridHealthService/diagnostics/version is Successful.
Connectivity Test Step 1 of 2 - Testing dependent service endpoints completed successfully.
Connectivity Test Step 2 of 2 - EventHub data upload procedure begins ...
Tenant Id is successfully collected during agent registration.
Server rejected Eventhub data upload, here is the exception: Microsoft.ServiceBus.Messaging.ServerBusyException: The request was terminated because the entity is being throttled. Error code : 50002. Sub error : 101. Please wait 4 seconds and try again. To know more visit https://aka.ms/sbResourceMgrExceptions and https://aka.ms/ServiceBusThrottlingS:N:ADHSPRODWUSEHSYNCIA:EVENTHUB:ADHSPRODWUSEHSYNCIA~22527,CL:30,CC:32,ACC:356250,LUR:WinEnd,LUT:2025-10-08T03:03:12.2035867Z,RC:1 TrackingId:<<< anonymized tracking ID>>> 0, SystemTracker:adhsprodwusehsyncia:eventhub:adhsprodwusehsyncia~22527, Timestamp:2025-10-08T03:03:13
at Microsoft.ServiceBus.Common.ExceptionExtensions.ThrowException(Exception exception)
at Microsoft.ServiceBus.Common.AsyncResult.End[TAsyncResult](IAsyncResult result)
at Microsoft.ServiceBus.Messaging.EventHubSender.Send(EventData data)
at Microsoft.Identity.Health.AgentV1.ConfigurationPowerShell.TestAzureADConnectHealthConnectivity.TestInsightServiceDataUploadProcedure()
Azure AD Connect Health agent could not communicate to the Health Service using port 5671. As a result, agent communication will fall back to use port 443, but use of port 5671 is recommended. Please allow outbound communication using port 5671.
Tenant Id is successfully collected during agent registration.
Server rejected Eventhub data upload, here is the exception: Microsoft.ServiceBus.Messaging.ServerBusyException: The request was terminated because the entity is being throttled. Error code : 50002. Sub error : 101. Please wait 4 seconds and try again. To know more visit https://aka.ms/sbResourceMgrExceptions and https://aka.ms/ServiceBusThrottlingS:N:ADHSPRODWUSEHSYNCIA:EVENTHUB:ADHSPRODWUSEHSYNCIA~22527,CL:30,CC:32,ACC:356837,LUR:IncomingUsage_ADHSPRODWUSEHSYNCIA-5,LUT:2025-10-08T03:03:54.9448143Z,RC:1 TrackingId:<<< anonymized tracking ID>>>, SystemTracker:adhsprodwusehsyncia:eventhub:adhsprodwusehsyncia~22527, Timestamp:2025-10-08T03:04:00
at Microsoft.ServiceBus.Common.ExceptionExtensions.ThrowException(Exception exception)
at Microsoft.ServiceBus.Common.AsyncResult.End[TAsyncResult](IAsyncResult result)
at Microsoft.ServiceBus.Messaging.EventHubSender.Send(EventData data)
at Microsoft.Identity.Health.AgentV1.ConfigurationPowerShell.TestAzureADConnectHealthConnectivity.TestInsightServiceDataUploadProcedure()
Azure AD Connect Health agent could not communicate to the Health Service using port 5671. As a result, agent communication will fall back to use port 443, but use of port 5671 is recommended. Please allow outbound communication using port 5671.
1 Reply
Try this:
- Enable Auto-Inflate for Event Hub
- Go to your Event Hub namespace in the Azure portal.
- Enable Auto-Inflate to allow dynamic scaling of TUs (up to 20 by default).
- If you need more than 20 TUs, submit a support request to Microsoft.
- Check Partition Load Distribution
- Ensure your data is evenly distributed across all Event Hub partitions.
- Use EventHubClient.Send without a partition key or with a round-robin strategy to balance the load.
- Monitor Usage Metrics
- Use Azure Monitor to check Event Hub metrics like Incoming Requests, Throttled Requests, and Throughput Units.
- This will help you identify spikes or bottlenecks.
- Allow Port 5671
- Although fallback to port 443 is possible, port 5671 is preferred for optimal performance.
- Ensure your firewall allows outbound traffic on port 5671.
- Retry Logic
- Implement exponential backoff in your retry logic to handle transient throttling gracefully.