Error decoding SFTP packet (9,4,9) :: Support Forum

@S. Ahmed: Thanks for your report.

Can you send me an email, so I can send you back a debug version of WinSCP to track the problem? Please include link back to this topic in your email. Also note in this topic that you have sent the email. Thanks.

You will find my address (if you log in) in my forum profile.

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manto Guest

Error decoding SFTP packet (22, 4, 22).

2018-10-04 17:42

Did anyone find solution for this error?

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manto Guest

Re: Error decoding SFTP packet (22, 4, 22).

2018-10-04 18:55

So it looks to be version issue

Basically we need to set the ‘Preferred SFTP protocol version’ to 3.

How to do this:
Edit the connection in WinSCP
Open the Advanced menu
Choose Advanced
This will bring up a new popup.
Under Environment click on SFTP.
Change ‘Preferred SFTP protocol version’ to 3
Save the changes.

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martin◆ Site Admin
Joined:: 2002-12-10
Posts:: 41,440
Location:: Prague, Czechia

Re: Error decoding SFTP packet (22, 4, 22).

2018-10-05

@manto: What SFTP server are you connecting to?

Please attach a full session log file showing the problem (using the latest version of WinSCP).

To generate the session log file, use /log=path_to_log_file command-line argument. Submit the log with your post as an attachment. Note that passwords and passphrases not stored in the log. You may want to remove other data you consider sensitive though, such as host names, IP addresses, account names or file names (unless they are relevant to the problem). If you do not want to post the log publicly, you can mark the attachment as private.

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Clément Guest

Re: What was the solution?

2024-02-29 23:49

Hello there, I'm pretty late on this but I got the same error too! "Error decoding SFTP packet (9, 4, 9)" can u provide a solution please? :)

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martin◆ Site Admin
Joined:: 2002-12-10
Posts:: 41,440
Location:: Prague, Czechia

Re: What was the solution?

2024-03-04

@Clément: Please attach a full session log file showing the problem (using the latest version of WinSCP). Use Debug 2 log level.

To generate the session log file, enable logging, log in to your server and do the operation and only the operation that causes the error. Submit the log with your post as an attachment. Note that passwords and passphrases not stored in the log. You may want to remove other data you consider sensitive though, such as host names, IP addresses, account names or file names (unless they are relevant to the problem). If you do not want to post the log publicly, you can mark the attachment as private.

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Clement Feuillet Guest

Re: What was the solution?

2024-03-04 23:34

@martin

cfeuillet@172.24.212.53.log (97.55 KB, Private file)

Description: Here's the log file, thanks a lot :)

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martin◆ Site Admin
Joined:: 2002-12-10
Posts:: 41,440
Location:: Prague, Czechia

Re: What was the solution?

2024-03-08

The server is violating SFTP specification.
Anyway, I've implemented a workaround:
Issue 2272 – Workaround for SFTP servers (Cisco) which omit message field from status response

Can you send me an email, so I can send you back a development version of WinSCP for testing? Please include a link back to this topic in your email. Also note in this topic that you have sent the email. Thanks.

You will find my address (if you log in) in my forum profile.

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martin◆ Site Admin

Re: Error decoding SFTP packet (9,4,9)

2024-03-22

The upload was failing because temporary file could not be created in the target directory.
The next version will handle that gracefully:
Issue 2277 – Fallback to nonresumable transfer when temporary target file cannot be created

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