When using an “FTP-over-Secure Sockets Layer” (FTPS) client which implements TLS 1.2, the file may not be uploaded as expected. In FileZilla this can present with files uploading over and over again, with a message being written to the Message Log, but no entries added to the “Failed transfers” tab.

550: The supplied message is incomplete. The signature was not verified.


This issue occurs because of a message-handling issue in Microsoft’s implementation of TLS 1.2.


Despite this issue having been reported and resolved back in 2012, Microsoft hasn’t fixed the issue in an update they push through Windows Updates or WSUS, instead, you’ll have to grab a hotfix.

You’ll need to submit your email address, to which Microsoft will sent a link to download the patch. Also, despite the knowledgebase article indicating that no reboot is required, when applied on our server, we had to reboot before the changes took.

Applies to

  1. Windows Server 2012 R2 Datacenter
  2. Windows Server 2012 R2 Essentials
  3. Windows Server 2012 R2 Foundation
  4. Windows Server 2012 R2 Standard
  5. Windows 8.1 Enterprise
  6. Windows 8.1 Pro
  7. Windows 8.1
  8. Windows Server 2012 Datacenter
  9. Windows Server 2012 Datacenter
  10. Windows Server 2012 Standard
  11. Windows Server 2012 Standard
  12. Windows Server 2012 Essentials
  13. Windows 8 Enterprise
  14. Windows 8 Pro
  15. Windows 8
  16. Windows Server 2008 R2 Datacenter
  17. Windows Server 2008 R2 Enterprise
  18. Windows Server 2008 R2 Standard
  19. Windows Server 2008 R2 Foundation
  20. Windows Server 2008 R2 for Itanium-Based Systems
  21. Windows 7 Ultimate
  22. Windows 7 Enterprise
  23. Windows 7 Professional
  24. Windows 7 Home Premium
  25. Windows 7 Home Basic
  26. Windows 7 Starter
  27. Internet Information Services 8.0


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