sql server login failed for user

There are three possible explanations: 1) they use SQL auth instead of integrated auth (which seems to be the most plausible one, since you example has an userid and password in conn string) 2) they use integrated auth and run in an app poll that uses a different credential or 3) they use integrated auth but the ASP app impersonates the caller, thus triggering constrained delegation: technet . telegram qr code login