Duplicate post:
https://winscp.net/forum/viewtopic.php?t=12996

Hosting service recently changed the format of their usernames.
The format is now "mydomain.com/person@mydomain.com".
Manual login from winscp prompt is OK, but cannot run successful scripting.

Does not connect and upload the file, it sits at an authentication prompt for a few seconds before disappearing, and fails.

Here is the Open command I am using:
open sftp://mydomain.com/person@mydomain.com:mypassword@mydomain.com -hostkey="ssh-rsa 1024 <the rest of my hostkey>".

I wonder if it is having trouble parsing the credentials.

Using 5.24 beta.

Let me know if there are additional details I could provide.