Eventhub throwing exception "Load balancing for event processor failed.","exception":"status-code: 500"

Question

Eventhub throwing exception "Load balancing for event processor failed.","exception":"status-code: 500"

Sanjay Godiya 5

Hi Community,

I am seeing an unexpected exception in my Java application logs. I have developed a Azure Eventhub producer-consumer application in Java SpringBoot. I am seeing below exception messages in my logs and I am not able to narrow down the root cause

2025-03-28T14:37:30.644Z WARN 1 --- [producer-consumer-service] [ctor-executor-3] c.a.m.e.i.ManagementChannel : status-code: 500, status-description: The service was unable to process the request; please retry the operation. For more information on exception types and proper exception handling, please refer to http://go.microsoft.com/fwlink/?LinkId=761101, errorContext[NAMESPACE: test-instance-01.servicebus.windows.net. ERROR CONTEXT: N/A, PATH: $management, REFERENCE_ID: mgmt:receiver, LINK_CREDIT: 0]

2025-03-28T14:37:30.644Z WARN 1 --- [producer-consumer-service] [oundedElastic-2] c.a.m.e.PartitionBasedLoadBalancer : {"az.sdk.message":"Load balancing for event processor failed.","exception":"status-code: 500, status-description: The service was unable to process the request; please retry the operation. For more information on exception types and proper exception handling, please refer to http://go.microsoft.com/fwlink/?LinkId=761101, errorContext[NAMESPACE: test-instance-01.servicebus.windows.net. ERROR CONTEXT: N/A, PATH: $management, REFERENCE_ID: mgmt:receiver, LINK_CREDIT: 0]","ownerId":"3ea4823b-5eb6-4c8d-903c-11caf012e01f"}

2025-03-28T14:37:30.644Z ERROR 1 --- [producer-consumer-service] [oundedElastic-2] a.s.i.e.i.EventHubsInboundChannelAdapter : Error occurred on partition: NONE. Error: {}

com.azure.core.amqp.exception.AmqpException: status-code: 500, status-description: The service was unable to process the request; please retry the operation. For more information on exception types and proper exception handling, please refer to http://go.microsoft.com/fwlink/?LinkId=761101, errorContext[NAMESPACE: test-instance-01.servicebus.windows.net. ERROR CONTEXT: N/A, PATH: $management, REFERENCE_ID: mgmt:receiver, LINK_CREDIT: 0]

I am using connection string to connect to eventhub, I have one queue for consumer, one for producer, each having one consumer group and one partition.

Any suggestion regarding above exception will be really helpful.

Thanks,
Sanjay

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Answer 1

Vinodh247 32,846 MVP Moderator

Hi ,

Thanks for reaching out to Microsoft Q&A.

Thanks for the detailed error message. From what you are seeing, this is a transient server-side error (status-code: 500) from Azure Event Hubs, specifically around the Event Processor load balancing logic. Let me help you narrow this down.

What the error means

status-code: 500 from Event Hubs is a generic server error indicating transient failure in Event Hubs' internal processing.

The specific call failing is on the management endpoint ($management), which is used by the Event Processor client to list partitions and coordinate load balancing.

PartitionBasedLoadBalancer is the Event Processor client module trying to balance ownership of partitions.

The Event Processor is failing to acquire partition ownership due to this transient failure and hence, logs Load balancing for event processor failed.

Most likely causes

Transient Azure Service Outage Event Hubs sometimes fails with 500s during internal throttling, upgrades, or other issues. These typically resolve themselves.

Excessive Load / Throttling

If your client (consumer) is polling too frequently or has aggressive retry logic, it can trigger throttling, which may show up as 500 errors.

  Load balancing makes calls every few seconds by default. If multiple instances are competing or aggressively retrying, it worsens the issue.
  
  Misconfiguration or resource constraints
  
     One partition, one consumer group, one processor – this is not ideal for load balancing logic (since load balancing expects multiple partitions to assign work). If there is only one partition, there is nothing to balance – but the client still tries.
     
        This might create unnecessary calls to `$management` endpoint.

Firewall / VNET / DNS issues (less likely)
- Sometimes misconfigured DNS resolution or IP firewall rules can cause $management endpoint failures. Check if any network security rule is interfering.

Fix that you can try:

Add retry logic and exponential backoff

These are transient errors. The Event Hubs SDK does internally retry, but you should ensure your code is resilient.

Reduce load on management endpoint

If you are using a single partition and consumer, consider disabling unnecessary load balancing logic (if using custom code) or simplifying the setup.

Add more partitions

Event Hubs is designed to work best when you have multiple partitions. With just one, the load balancing logic becomes almost redundant and may lead to unexpected retries or behavior.

Action: Increase the partition count of your Event Hub (requires recreation).

Please feel free to click the 'Upvote' (Thumbs-up) button and 'Accept as Answer'. This helps the community by allowing others with similar queries to easily find the solution.

Sanjay Godiya 5 Reputation points

2025-03-30T13:24:38.15+00:00

Thanks for the response @Vinod247
Sanjay Godiya 5 Reputation points

2025-03-30T13:25:13.1933333+00:00

Hi Vinodh,

Thanks for the detailed explanation about the issue and pointing to the root cause. I want to inform that we have 1 partition 1 consumer group setup in one more environment(dev) for same application although we don’t see such exceptions there.

I will see if I can work on any of the suggestions mentioned above on our new environment(test).

Thanks,

Sanjay
J N S S Kasyap 2,040 Reputation points Microsoft External Staff Moderator

2025-03-31T02:39:12.6333333+00:00

@Sanjay Godiya
We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
J N S S Kasyap 2,040 Reputation points Microsoft External Staff Moderator

2025-04-01T01:46:07.3+00:00

@Sanjay Godiya
We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
Sanjay Godiya 5 Reputation points

2025-04-01T08:26:01.8366667+00:00

Hi @J N S S Kasyap ,

The assumption made in the response of @Vinodh247 is not correct, Event hub does work with one partition one consumer setup without throwing any load balancing error so his answers was not helpful. The root cause of the exception was management endpoint was not able to find any partition (not even one partition which I had created) for given connection. The Event hub namespace should not include “.servicebus.windows.net” in configuration. Because of the extra domain name, management endpoint was not able to find the partition and queue and it was throwing load balancing exception.

Thanks,

Sanjay
J N S S Kasyap 2,040 Reputation points Microsoft External Staff Moderator

2025-04-02T03:57:57.97+00:00
@Sanjay Godiya

The Event Hub namespace was incorrectly configured. The user mistakenly included .servicebus.windows.net in the namespace when setting up the connection.

Why This Caused the Issue:

The Event Hub management endpoint ($management) is responsible for querying partition information.

If the namespace is incorrect, the Event Hubs SDK fails to locate partitions, leading to a 500 error in the load balancer.

Since the load balancer couldn't find any partitions, it kept retrying and throwing errors

Fix the namespace configuration by removing, servicebus.windows.net from the connection settings.

The correct namespace should be just the Event Hub namespace, not the full domain name

I hope this information helps. Please let us know if you have any further queries. If the issue still persisits I am happy to assist with more details.
J N S S Kasyap 2,040 Reputation points Microsoft External Staff Moderator

2025-04-03T00:16:34.3666667+00:00

@Sanjay Godiya
We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
J N S S Kasyap 2,040 Reputation points Microsoft External Staff Moderator

2025-04-04T00:21:56.06+00:00

@Sanjay Godiya
We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.

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Eventhub throwing exception "Load balancing for event processor failed.","exception":"status-code: 500"

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