Issue installing "UMEP for processing"

[Lucille-pixel]

I've triied severals times to instal the extension "UMEP for processing" on my QGIS but it failled. The error message says : "Impossible de charger l'extension 'processing_umep' provoque une erreur lors de l'appel à sa méthode classFactory() " which means : "impossible charging the extension 'processing_umep' error during the call of the methode classFactory()".
My friends are having the same issue. Does anyone know something about it ? How can it be fixed ? Is it an internal error ?