Hi @Lily Zhang(Techsun) Thanks for reaching out. Could please let me know if the issue is intermittent usually most of the failures are transient in nature, please make sure you haven't turned off client retry. Client retry will automatically retry in the case of transient failures. You can find more on retry policy at
https://learn.microsoft.com/en-us/azure/architecture/best-practices/retry-service-specific#service-bus
https://msdn.microsoft.com/en-us/library/microsoft.servicebus.retrypolicy.aspx
Please let me know if you have any further queries. I would be happy to assist you.