Physical connection is not usable - MS SQL DB 2019

Question

On the 21st February 2024,

One of our internal applications had encountered and error like the below.

[ODBC Driver 18 for SQL Server]SMux Provider: Physical connection is not usable [xFFFFFFFF].

With how far we have gone now, we see that this issue is very much to do with a temporary network disruption based on the article from Microsoft, https://learn.microsoft.com/en-us/archive/msdn-technet-forums/95fe26d2-2e6c-4c6b-b02d-10794e92dc7a which the experts claims as a bit outdated.

The entities associated in the infra are,

1. Azure VMs based on Windows with Windows (Windows Server 2019 Datacenter) where the application is installed and configured
2. Azure SQL Database
3. The Application is a Delphi and DOT NET based client served through Citrix

Has anyone encountered this and if yes, I would appreciate suggestions on how to prevent this from happening again.

Answer 1

Based on the provided context, the error message "Physical connection is not usable" is a general network error that can occur when connecting to a SQL Server instance. This error can be caused by a variety of issues, including network disruptions, configuration issues, or firewall blocking the connection. To resolve this issue, you can try the following steps:

1. Check the network connectivity between the client and the SQL Server instance.
2. Verify that the SQL Server instance is running and configured to allow remote connections.
3. Check the firewall settings to ensure that the SQL Server port is open.
4. If the issue persists, try restarting the SQL Server service.

It is also recommended to review the troubleshooting steps provided in the following Microsoft articles:

• A network-related or instance-specific error occurred while establishing a connection to SQL Server
• Consistent SQL Server network connectivity issues

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References:

• A network-related or instance-specific error occurred while establishing a connection to SQL Server
• Consistent SQL Server network connectivity issues

Answer 2

Kennedy Noel

Please do check this doc

Use smart retry/back-off logic to mitigate the effect of transient failures It will be difficult to pinpoint the exact cause of the issue because users who faced similar issue were able to get it resolved using different route. This error can have multiple causes, so it’s essential to investigate thoroughly. I would suggest checking this https://stackoverflow.com/questions/22714569/cannot-get-rid-of-physical-connection-is-not-usable-exception

SQLSTATE = 08S02, SMux Provider Physical connection is not usable

Answer 3

We are making our best efforts to connect with DB experts within our organization to evaluate these options that you have put forth. Allow us to come back to you before you decide to resolve this please.