The %1!s! is already attached and cannot be attached again. Detach it and try again.
Community Notes
As the message says really. Had some issues with when building packages programmatically, and calling IDTSPath90.AttachPathAndPropagateNotifications when I shouldn't have, or at least without passing in the correct parameters. Check your code; you are probably referencing a previous component by mistake.
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Pipeline HRESULT codes for SQL Server Integration Services. Each code has an individual topic page with the full description and related codes. You can also include any additional information about symptoms, cases and fixes as you find the. Please contribute your findings.