Best practices to avoid the issue
Corporate network filters often block automated, programmatic web requests initiated by application scripts. solar putty unable to download winscp libraries portable
The most definitive way to resolve the error is to bypass Solar-PuTTY's internal downloader entirely. You can pull down the exact official libraries yourself and place them into the folder where Solar-PuTTY expects to see them. Best practices to avoid the issue Corporate network
The official SolarWinds Quick Reference Guide confirms that this is standard behavior: solar putty unable to download winscp libraries portable
WinSCPnet.dll (The library often required for .NET-based integration) Solar-PuTTY - SolarWinds THWACK