Salut,
Suite à une mise a jour réussie des paquets -myPhP-…, de ssowat et de la Moulinette,
je n’accède pas au backoffice de Wordpress.
Message d’erreur "ERROR: No user found in server variables."
Vers quoi s’orienter ?
rq: installation sur RaspberryPi B+
Pour ce type de problème je l ai résolu en réinstallant l app. 
Cependant après enquête, Il s’agit d’un problème avec l’extension HTTP Authentication pour WP.
Pour cela supprimer via ftp soit manuellement si possibilité.
For this type of problem I have it solved by reinstalling the app.
However, after investigation, it is a problem with the HTTP Authentication plugin for WP . it was activate.
To remove it manually via ftp if possible .
only one but my friend, if you delete the plugin then how the f would you get in since it does a error on the username, lets bump it up up up!!!
5 years ago this issue!?
I just ran into this issue as well and I wrote a new post about it: Wordpres migration fails
For me, the issue is that my Wordpress user table does not include the YNH account because it’s from an even older install. Disabling the http-authentication plugin by manually editing active_plugins under wp_options allowed me to see the login page and use my non-SSO account like I have in the past
Welcome to the future!