Just a day ago, one of my friend sent me email requesting help with following error:
is not a valid Win32 application. (Exception from HRESULT: 0x800700C1)
In fact this is not SQL Server error but it is of .NET application. The solution of this error is just changing configuration of IIS7.
Go to IIS.
Click on Application Pool.
Look for your web application in application pool.
Go to Advanced Settings by right clicking on previously selected application pool.
Enable 32-Bit Applications by checking it.
Reference : Pinal Dave (https://blog.sqlauthority.com)