Can't open Worldserver packages anymore after installing Service Pack 1 for Studio 2021

Dear Community,

Yesterday I installed Service Pack 1 for Studio 2021 Freelance and ever since I cannot open Worldserver packages anymore. I already tried deactivating and reactivating the plugin SDL WorldServer Package Converter that is needed to open Worldserver packages in Studio 2021 in the first place, but it didn't help.

This is the error message (German version of Studio 2021):

Methode nicht gefunden: "Sdl.ProjectApi.lApplicationSdlProjectApi.ApplicationFactory.CreateApplication()“.

This is my version: SDL Trados Studio 2021 SR1 -

Any ideas?

Kind regards,