When I am trying to add the Second Server for the SQL AlwaysON Group, I end up with following error

After Serious Search in Internet, Found the solution which resolved the above issue

After Serious Search in Internet, Found the solution

Run the Below Command in Primary Server,

Here windowstechpro\SFBDB2$ is Domain\SecondNode$

use [master]

GO

CREATE LOGIN [windowstechpro\SFBDB2$] FROM WINDOWS

GO

GRANT CONNECT ON ENDPOINT::[Hadr_endpoint] TO [windowstechpro\SFBDB2$]

GO

Run the Below Command in Second Server,

Here windowstechpro\SFBDB1$ is Domain\PrimaryNode$

use [master]

GO

CREATE LOGIN [windowstechpro\SFBDB1$] FROM WINDOWS

GO

GRANT CONNECT ON ENDPOINT::[Hadr_endpoint] TO [windowstechpro\SFBDB1$]

GO

Then tried to add the Second Node again and found I am able to add it without any other issues.