Issues with starting a translation in SDL Trados Studio

Dear all,

I have been having issues with starting a translation in SDL Trados Studio (2019 version).

When I try to open a file for translation, I have several error messages like:

-Unexpected exception when initializing view part Fragment matches

- Key not found

- Cannot access site for type Sdl.TranslationStudi.Editor.TranslationEditor.TranslatableDocumentViewPart before the view part has been initialized.

Kindly help please!