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Error 19 - Physical connection is not usable

 

 

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Error 19 - Physical connection is not usable.


Applies to: Azure VM, IIS Web Server, Windows Server 2019, Azure SQL Database.

Date created: December 19, 2019.
 

Problem Description.
 

We migrated an IIS Web Server from a Windows Server 2012 (Azure IaaS VM) to Windows Server 2019 (a new Azure IaaS VM) and we used endpoints to connect from the Web server to the Azure SQL Database.

When the users started to use our Web applications on the newly migrated Web server, they started to receive randomly the following errors:

A transport-level error has occurred when receiving results from the server. (provider: Session Provider, error: 19 - Physical connection is not usable)

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception details: System.Data.SqlClient.SqlException: A transport-level error has occurred when receiving results from the server. (provider: Session Provider, error: 19 - Physical connection is not usable)

Source Error:

An unhandled exception occurred during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace: SqlException (0x80131904): A transport-level error has occurred when receiving results from the server. (provider: Session Provider, error: 19 - Physical connection is not usable).

 

 

 


Cause.


We were using Azure Virtual Network service endpoints to allow hosts located on Azure virtual networks access an Azure SQL Database.

Timeouts and errors have been reported by some customers when they enable endpoints or virtual network firewall rules. This means that errors shown above are not related to Azure SQL Database and are more an Azure Networking related issue. An Azure support ticket should be created.


Workaround.


In our scenario, we disabled endpoints and all connections coming from clients hosts and the Web server got connected to the database successfully. No more errors 19 were reported.

Allowing connections through an appliance like Fortinet or directly over the Internet are some possible workarounds while Azure Support fix the issue for you.
 

 

 

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