This request is being tracked already:
Issue 1955 – Allow uploading edited files using the main connection
You can vote for it there.

Hi Martin,

I guess you're right. It only works in some situations. Within a very short period of time, PuTTY sometimes allows two sessions to be opened using the same verification code. I'm not sure why either, so I'll check with our IT team later.

By the way, is there any way to let WinSCP edit/upload files using the same session as the initial connection, instead of opening a new one?

Lastly, thank you for your patience and for taking the time to reply to my questions.

Can you open two sessions in WinSCP using the same code? Please post logs for that? Can you post logs of opening two sessions using the same code in PuTTY?

In theory, as long as the verification code is still valid, the server should allow a new connection even if the same code is used within its validity period.

For example, I can open multiple PuTTY connections within a very short period using the same verification code without any issues.

Yes, I did try waiting for a new verification code. In that case, it usually works. However, it feels like an unnecessary workaround since the original code is still valid.

I do not know, it's the server that validates the code. So did you try waiting for a new code? Does it change anything?

Yup. For the second prompt, I copied the new verification code again.

I'm not sure if the validity period is too short, so the verification code happened to remain the same. However, would that still be an issue?

The screencast confirms that, doesn't it? The one-time password seems to really work just one time. What if you use new one-time password for the second prompt?

Maybe you can take a look at this attachment.

You wrote that saving works for some time. But I do not see that in the log. It is failing from the very first save. So how is it? It looks like you are actually not able to use your one-time-password second time for the background session.

Sorry for the late reply. Here is the log file.

Thanks you get an OTP prompt for the first save is expected, as edited files are uploaded using a separate connection. For the "No supported authentication methods available" problem, please post session log file.

Hi,

I am experiencing an issue when using WinSCP with a server that requires a password and a verification code for authentication.

Steps to reproduce:

• Connect to the server using WinSCP.
  
• Enter the password and verification code.
  
• Login succeeds.
  
• Open a remote file and edit it (tested with both the internal editor and an external editor).
  
• Save the file.
  

At this point, WinSCP prompts for the verification code again. If I continue editing and saving files within a short period of time, eventually the connection fails with:

No supported authentication methods available