InvalidOperationException: Cannot Open when State is Open.

The error message "InvalidOperationException: Cannot Open when State is Open" typically occurs when you try to open a connection to a database that is already open.

To fix this issue, you should first check if the connection is already open before attempting to open it again. You can do this by calling the "State" property of the connection object, which will return the current state of the connection.

For example, you can check if the connection is open like this:

if (connection.State == ConnectionState.Open)
{
    // Connection is already open, do not attempt to open again
}
else
{
    // Connection is not open, open it now
    connection.Open();
}

Make sure to always close the connection when you are finished using it, to avoid this issue in the future.