Cannot Upload Large File to Azure Blob Using SFTP :: Support Forum

jbaker85
Joined:: 2022-12-16
Posts:: 2

Cannot Upload Large File to Azure Blob Using SFTP

2022-12-16 19:04

I'm using WinSCP Version 5.21.6 on Windows 10.0.19044 to connect to an Azure blob container. I'm trying to upload a 10GB dummy file using SFTP and it interrupts and starts over every time.

I'm running with 'Optimize connection buffer size' turned OFF and server response timeout set to 60 seconds. Also, following Microsoft's guidance for WinSCP, I have disabled 'Transfer resume/transfer to temporary filename'.

FileZilla has no problem uploading the full file. Can anyone help me figure out what settings might be causing the connection to break?

Winscp.log (25.17 KB)

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martin◆ Site Admin
Joined:: 2002-12-10
Posts:: 41,453
Location:: Prague, Czechia

Re: Cannot Upload Large File to Azure Blob Using SFTP

2022-12-19

Thanks for your report. I'll look into it.
Meanwhile, try to temporarily turn off rekey on data:
https://winscp.net/eng/docs/ui_login_kex

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jbaker85
Joined:: 2022-12-16
Posts:: 2

Still Interrupting

2022-12-21 21:14

Thanks for that advice, it definitely seemed to improve the duration of the connection and it was able to transfer the majority of the file before once again failing and restarting. The log shows the Azure side initiated key re-exchange which somehow broke the connection.

2022-12-21 13:18:10.483 Remote side initiated key re-exchange
2022-12-21 13:18:10.485 Doing ECDH key exchange with curve nistp256 and hash SHA-256
2022-12-21 13:18:12.093 Initialised AES-256 SDCTR (AES-NI accelerated) [aes256-ctr] outbound encryption
2022-12-21 13:18:12.093 Initialised HMAC-SHA-256 outbound MAC algorithm
2022-12-21 13:18:12.864 Initialised AES-256 SDCTR (AES-NI accelerated) [aes256-ctr] inbound encryption
2022-12-21 13:18:12.864 Initialised HMAC-SHA-256 inbound MAC algorithm
2022-12-21 13:43:03.738 Remote side initiated key re-exchange
2022-12-21 13:43:03.739 Doing ECDH key exchange with curve nistp256 and hash SHA-256
2022-12-21 13:43:13.934 Network error: Software caused connection abort
2022-12-21 13:43:13.956 Connection was lost, asking what to do.
2022-12-21 13:43:13.956 Asking user:
2022-12-21 13:43:13.956 Network error: Software caused connection abort ()

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Cannot Upload Large File to Azure Blob Using SFTP