#73 Can't upload any file via SFTP

[Anonymous]

Originally created by: Ar-Paramir

Description

I can connect to a remote SFTP server, see the files, browse the folders, and download files, but cannot upload files. I tried it with several different servers, the result is the same. During one of the attempts, several empty folders were uploaded, but not all the folders, and no files inside. Tried a synchronization mode, didn't work either. The error in the log is:
[20:24:47] INFO - Upload failed: Upload failed: Authentication failed: SSH2 fallback rejected 193.106.69.137:22 because the host key changed
The host key is stored in ~/.ssh/known_hosts. I removed it and accepted the key again, no result. FileZilla uploads the files perfectly with the same settings. In the transfer queue, the uploaded files are marked with green ticks, but in fact, the upload failed. AeroFTP works with default settings.

Steps to Reproduce

1. Set up the SFTP server
2. Connect, accept the key
3. Browse to a folder
4. Try to upload
5. Receive the error message, upload failed

Expected Behavior

To be able to upload the files

Actual Behavior

"Host key changed" warning while the key was saved a minute ago and nothing changed, upload failed as a result. AeroFTP turns to be useless to work with files via SFTP.

Environment

• OS: TUXEDO (=Ubuntu 24.04 +KDE)
• AeroFTP Version: 3.2.6, installed via .deb package
• Protocol: SFTP

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Submitted via aeroftp.app (www.aeroftp.app)

[Anonymous]

Originally posted by: axpnet

Hello @Ar-Paramir,

Thank you for the detailed report and for providing the logs.

We are currently investigating this behavior. On our end, we have successfully tested SFTP connections with various configurations (including private NAS setups) without encountering this specific authentication fallback error.

The error SSH2 fallback rejected... because the host key changed is peculiar, especially since you’ve already cleared your ~/.ssh/known_hosts. It seems like there might be a mismatch in how the key is being cached or verified during the upload process specifically.

While we perform deeper tests to replicate your environment:

• Could you try to toggle the connection settings? For instance, if you are using a specific encryption algorithm or compression, try switching to default or alternative ones to see if the "fallback" error persists.

• Are you using a specific key format (e.g., RSA, ED25519) and does your private key have a passphrase?

• Permissions: Double-check if the user running AeroFTP has consistent write permissions to the local folder where the app might be storing its internal session data.

We will continue our internal testing and keep you updated. Please let us know if changing any connection parameters leads to a different result!

[Anonymous]

Originally posted by: Ar-Paramir

Hello,

Thank you for your quick response. I'm not sure I see how to toggle the connection settings according to your recommendations. I don't see such options as encryption algorithm or compression. The only things I enter are server, port, username, password (these seem to be correct, since I can successfully connect to the server), connection timeout, remote/local path (changing these options don't affect the fallback error).

I run AeroFTP as a standard user. I noticed that a ~/.config/aeroftp/ folder had rwx (700) permissions, I changed the permissions for all subfolders and files to rwxr-xr-x (755), but it didn't change the issue.

I also noticed some interesting things:
my Dropbox and Google Drive work normally via OAuth2, I can upload files there. So, the issue affects specifically SFTP connections.
in SFTP remote folders I can
create new folders
delete new and old folders
download existing filesrename existing files
delete existing files
No key issues during these actions! So, everything works fine... except uploading local files to SFTP servers.

Also, in a debug window I see "Credential storage: gnome-keyring / Secret Service", but I use KDE and gnome-keyring isn't installed for me. Can it be the reason of the error? But at the same time, why only uploading the files via SFTP is broken? Looks weird. I hope you'll find a solution to sort it out.

Kind regards,
Rodion

1 квіт. 2026 р., 00:05 з @.***:

axpnet> left a comment > (axpdev-lab/aeroftp#73) https://github.com/axpdev-lab/aeroftp/issues/73#issuecomment-4164448921

Hello > @Ar-Paramir https://github.com/Ar-Paramir> ,

Thank you for the detailed report and for providing the logs.

We are currently investigating this behavior. On our end, we have successfully tested SFTP connections with various configurations (including private NAS setups) without encountering this specific authentication fallback error.

The error SSH2 fallback rejected... because the host key changed is peculiar, especially since you’ve already cleared your ~/.ssh/known_hosts. It seems like there might be a mismatch in how the key is being cached or verified during the upload process specifically.

While we perform deeper tests to replicate your environment:

Could you try to toggle the connection settings? For instance, if you are using a specific encryption algorithm or compression, try switching to default or alternative ones to see if the "fallback" error persists.

Permissions: Double-check if the user running AeroFTP has consistent write permissions to the local folder where the app might be storing its internal session data.

We will continue our internal testing and keep you updated. Please let us know if changing any connection parameters leads to a different result!

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