sftp external storage broken with "No compatible server host key algorithms found"

[jgoerzen]

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Steps to reproduce

1. Attempt to set up an external storage with rsync.net at a SFTP destination
2. It shows login failure in the GUI.
3. Server log shows Error: No compatible server host key algorithms found at /var/www/owncloud/3rdparty/phpseclib/phpseclib/phpseclib/Net/SSH2.php#1551

Expected behaviour

External storage should be established.

Actual behaviour

It is unable to establish the SSH link.

Server configuration

Operating system:

Linux

Web server:

Apache
Database:
Mysql
PHP version:

Nextcloud version: (see Nextcloud admin page)

21.0.2

Updated from an older Nextcloud/ownCloud or fresh install:
Updated
Where did you install Nextcloud from:
Nextcloud.com
Signing status:

Signing status

No errors have been found.

Are you using external storage, if yes which one: local/smb/sftp/...

sftp

Are you using encryption: yes/no

no

Are you using an external user-backend, if yes which one: LDAP/ActiveDirectory/Webdav/...

no

Client configuration

Browser:
Firefox
Operating system:
Linux

Logs

See above

See Also

This Owncloud bug looks very similar:

owncloud/core#38353

[szaimen]

I suppose this is still valid on NC21.0.3?

[jgoerzen]

Yes, it is. Thanks.

[szaimen]

cc @icewind1991

[szaimen]

Hi, please update to 24.0.9 or better 25.0.3 and report back if it fixes the issue. Thank you!

My goal is to add a label like e.g. 25-feedback to this ticket of an up-to-date major Nextcloud version where the bug could be reproduced. However this is not going to work without your help. So thanks for all your effort!

If you don't manage to reproduce the issue in time and the issue gets closed but you can reproduce the issue afterwards, feel free to create a new bug report with up-to-date information by following this link: https://github.com/nextcloud/server/issues/new?assignees=&labels=bug%2C0.+Needs+triage&template=BUG_REPORT.yml&title=%5BBug%5D%3A+