We have a Standard Azure Service Bus subscription. We have started seeing the following error today - Microsoft.ServiceBus: ConnectionsQuotaExceeded for namespace

Hi @Jadhav Vikrant (Contractor) Greetings! Welcome to Microsoft Q&A forum. Thank you for posting this question here.

The error message indicates that the maximum number of connections to the service bus namespace has reached, and it cannot process new connections t serve the function app. The issue is likely caused by two common scenarios

1. Dead-letter queue A reader is failing to complete messages and the messages are returned to the queue/topic when the lock expires. It can happen if the reader encounters an exception that prevents it from calling BrokeredMessage.Complete. After a message has been read 10 times, it moves to the dead-letter queue by default. This behavior is controlled by the QueueDescription.MaxDeliveryCount property and has a default value of 10. As messages pile up in the dead letter queue, they take up space.

To resolve the issue, read and complete the messages from the dead-letter queue, as you would from any other queue. You can either use Azure Service Bus Explorer that enables manual moving of messages between queues and topics or code like this can help move them all at once.

1. Receiver stopped. A receiver has stopped receiving messages from a queue or subscription. The way to identify the issue is to look at the active message count. If the active message count is high or growing, then the messages aren't being read as fast as they're being written. Hope this helps to identify the cause for the issue. Please let us know if you need any additional assistance after reviewing the above mentioned steps.