WSL2 Azure SQL Connection Issue

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WSL2 Azure SQL Connection Issue

Asiful Nobel 196

I am running a .NET 6 web app on WSL2 (Windows Sub-system for Linux), but having connection issue with Azure SQL connection. I keep getting the following exception.

System.InvalidOperationException: The exception handler configured on ExceptionHandlerOptions produced a 404 status response. This InvalidOperationException containing the original exception was thrown since this is often due to a misconfigured ExceptionHandlingPath. If the exception handler is expected to return 404 status responses then set AllowStatusCode404Response to true.  
---> System.Data.Entity.Core.EntityException: The underlying provider failed on Open.  
---> System.Data.SqlClient.SqlException (0x80131904): A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 40 - Could not open a connection to SQL Server)  
at System.Data.ProviderBase.DbConnectionPool.CheckPoolBlockingPeriod(Exception e)  
at System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)  
at System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)  
at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection)  
at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection)  
at System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)

I am using the connection string in the following format.

Server=tcp:[ServerName].database.windows.net,1433;Initial Catalog=[DatabaseName];Persist Security Info=False;User ID=[UserName];Password=[Password];MultipleActiveResultSets=False;Encrypt=True;TrustServerCertificate=False;Connection Timeout=30;

This works on Windows, but it does not work on WSL2. I checked with tcpping and nslookup that the database server and port is reachable, but the app cannot connect to it for some reason.

Does anyone know why this is happening and is there a solution?

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Answer 1

Alberto Morillo 34,671 MVP Volunteer Moderator

It seems it cannot access the Azure SQL Database. Have you added the public IP address of your Internet connection to the whitelist of Azure SQL Database firewall. Please read here to know how.

It could be also related to DNS resolution. If you the server [ServerName].database.windows.net, the ping should fail but when the ping fails it returns the current IP address of the Azure SQL Database server. If you don't see that then the issue may be related to DNS resolution from your computer.

We need to open the ports from the WSL2 please read this article. Here you will find more information about networking and WSL2,

Here you will find all steps to configure WSL2 to access a SQL Server/SQL Azure instance.

Make sure the corporate network allows outbound traffic on port TCP 1433.

Asiful Nobel 196 Reputation points

2022-07-01T19:38:15.877+00:00

@Alberto Morillo Yes, the client IP address has been added on the firewall. The app can open the SQL connection on the same machine from the Windows Host. But it does not work on the Linux sub-system (WSL2). I cannot reach the database IP with ping. ping command resolves the IP address, but all packets are lost.

Can it be a host WIndows 10 firewall issue? The app cannot access the SQL Server on the Windows host either when it is running on WSL2 Ubuntu.

Update: Turning the Windows firewall off didn't work. Ping still lost all packets.
Alberto Morillo 34,671 Reputation points MVP Volunteer Moderator

2022-07-01T19:57:31.51+00:00

We need to open the ports from the WSL2 please read this article. Here you will find more information about networking and WSL2,
Alberto Morillo 34,671 Reputation points MVP Volunteer Moderator

2022-07-01T20:03:53.347+00:00

More instructions can be found here.

I updated my original answer with all the instructions and references to configure WSL2.
Asiful Nobel 196 Reputation points

2022-07-01T20:44:42.157+00:00

@Alberto Morillo I followed the stackoverflow answer, but it did not work. So, I added a new inbound rule in firewall to let any program access anything on any protocol, but that did not work either. Maybe there is something blocking it as it's an office laptop. Thanks for the help.
Alberto Morillo 34,671 Reputation points MVP Volunteer Moderator

2022-07-01T20:50:12.617+00:00

Can you temporarily disable any security software like Avira, Sophos, Carbon Copy, etc?
Asiful Nobel 196 Reputation points

2022-07-02T08:55:58.203+00:00
@Alberto Morillo There isn't anything like that. Today I tested again with the Windows firewall turned off and local Windows SQL Server. Ping worked with IP of Windows Host, but the app couldn't open a SQL connection. I am on my home network.

I tried with the following connection strings -

Data Source=tcp:[ip-address],1433;Initial Catalog=[db-name];User Id=[user];Password=[password]; Data Source=[ip-address];Initial Catalog=[db-name];User Id=[user];Password=[password];

Update: I was able to access the SQL Server on Windows Host. The server was not listening on all ports, so I had to change it from Management Console after adding the firewall rule to allow connection from WSL.
Alberto Morillo 34,671 Reputation points MVP Volunteer Moderator

2022-07-02T13:12:08.357+00:00

So the ports were closed. Glad to know you were able to make the appropiate adjustements on the firewall.

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WSL2 Azure SQL Connection Issue

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