You cannot use Pageant for this.
Pageant is intended for an interactive human use, not for automation.
See also https://winscp.net/eng/docs/faq_scheduler

Use -passphrase switch. Or remove the passphrase from the primate key altogether.
https://winscp.net/eng/docs/faq_passphrase#automating

I'm not that technical, but have resources that are stumped so I thought I would post this.

We have a client we are trying to send SFTP data to that uses private/public/passphrase logins. We are using Pageant to send the "key" so we can automatically login. We have some PDF manipulation tools that run as a service and using VBScripting within this application we are building a batch file with the login details, then running the batch file from this same service. It fails.

When we run the batch file when just logged in to the server, it works perfectly.

The login used by the Service & the login I use when I remote in to the Server2016 machine are the same, both Administrator.

Thoughts?