kio_sftp: "The host key for this server was not found, but another type of key exists."

[Michael Schuerig <michael.lists@schuerig.de>]

Network folders in Dolphin don't work for me anymore after some recent update. 
I'm using a current unstable system. sftp on the commandline continues to work 
as before.

The error message I get in Dolphin is

> The host key for this server was not found, but another type of key exists.
> An attacker might change the default server key to confuse your client into
> thinking the key does not exist. Please contact your system administrator.

My connection attempts were to machines running Debian/testing and macOS 
(10.13.6).

I've found a couple of similar errors on the web

https://askubuntu.com/questions/598455/problems-with-kio-sftp-in-dolphin-konqueror
https://bugs.kde.org/show_bug.cgi?id=274170

However, they have in common that they are several years old. If they are 
still pertinent, I ought to have seen this problem for a long time. Which is 
not the case. Things worked flawlessly until recently.

Notwithstanding, I tried forcing the use of an RSA key like this

  ssh -o HostKeyAlgorithms=ssh-rsa user@server

but it didn't result in any noticeable change. ~/.xsession-errors contains 
contains informative entries for log_kio_sftp, but no error messages.

Any ideas what might be going wrong and what I can do about it?

Michael

-- 
Michael Schuerig
mailto:michael@schuerig.de
http://www.schuerig.de/michael/