Hello,
This topic saved my life, my yunohost instance lost access to the webmin and in SSH it was unable to execute the command yunohost. After un attempt to do apt-get install yunohost that said error you have to do an yunohost postinstall. But I want keep my domain name so I searched in the forum and found your tips. Thanks a lot for that.
An happy yunohost user for at least 3 years 