Azure Web App Error, No such host is known

Question

When Running the web App locally there is no issue to connect to the DB,

after deploying the Web App to Azure the DB(Also Azure) connection attempt throws the following error:

[Win32Exception (0x80004005): No such host is known]

[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: 0 - No such host is known.)]

The DB FW Settings: Allow access to Azure services: is set ON

Any Idea on how I can trouble shoot/ Resolve this issue?

Solution 1

This could be caused by pasting your connection string in after Data Source=

connectionString="Data Source=Server=...."

Instead, it should be

connectionString="Server=...."  

Solution 2

Make sure you don't override connection string in portal config

Solution 3

Worked yesterday, stopped working today. Redeployed my app and it started working again.

Solution 4

[![In my case i dont know how in the virtual network and firewall option the option in red was pressed I turned on to allow azure service can connect the sql server, and it did the trick][1]][1]

Solution 5

I was missing Service Bus connection, that can be found below:

Azure Function > Integrate > Outputs > Azure Service Bus > Service Bus connection

Last two may be something else for you.

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Comments

[Jeremy Holovacs]

Ridiculously, this same exact thing happened to me.

[Rahatur]

In my case happening at random!