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SFTP file upload download issue.

Senthil kumar 110 Reputation points
2026-04-21T06:26:30.1933333+00:00

Dear all,

already i developed sftp file upload and download with Renchi and SSH.net. For the weak RSA key encryption our IT support blocked RSA key encryptions so winscp is another option to implement personally i feel little complicated WINSCP so any other option implement for sftp connection.

Thanks.

Developer technologies | C#
Developer technologies | C#

An object-oriented and type-safe programming language that has its roots in the C family of languages and includes support for component-oriented programming.

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  1. Jack Dang (WICLOUD CORPORATION) 17,420 Reputation points Microsoft External Staff Moderator
    2026-04-21T07:50:21.1033333+00:00

    Hi @Senthil kumar ,

    Thanks for coming back and sharing what resolved it on your side.

    For anyone else who runs into something similar, keeping the SFTP library fully up to date is important because newer releases usually include fixes for key exchange, cipher support, and security policy compatibility. It is also a good idea to verify the server-supported algorithms with your IT team and test the connection again after any package upgrade, especially in environments where older encryption methods have been disabled.

    If the latest package is working now, that is generally the better path than switching tools right away. If you ever need an alternative later, choose one that is actively maintained and supports the same security requirements your server enforces.

    If my explanation to your solution was helpful to you, I would greatly appreciate it if you could follow the instructions here so others with the same problem can benefit as well.

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  1. Q&A Assist
    2026-04-21T06:26:40.62+00:00
    AI generated content. This question contains an answer created with AI from Q&A Assist. Learn more

    Renci SSH.NET versions before 2020.0.0 are known to be incompatible with some modern SFTP endpoints because of algorithm support, including stronger RSA requirements. The recommended approach is to move to a version that explicitly supports the newer algorithms instead of relying on older builds that use weak RSA.

    From the documented supported client list, SSH.NET 2020.0.0 and later are supported SFTP clients when stronger algorithms are required. So instead of switching to WinSCP if that feels too complex, update the existing SSH.NET dependency to at least 2020.0.0 (or newer) and configure it to use only strong key algorithms that comply with the organization’s security policy.

    If the SFTP server is Azure Blob Storage with SFTP enabled, make sure the client library version is in the supported list and that the key/cipher configuration matches the server’s supported algorithms.

    References:

    2 people found this answer helpful.

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