When you are trying to access the project, you receive this error message:

Unexpected exception when initializing view part Fragment Matches

The translation memory window is not available​



Or when trying to access the Editor view:

Cannot access site for type Sdl.TranslationStudio.Editor.Previews.InternalPreview.InternalPreviewViewPart before the view part has been initialized.

1. Close Trados Studio.  
2. Press the Windows and R keys at the same time, enter %temp% in the blank field, and then click on OK. Delete all the files and folders, if possible. 
3. (optional) Turn off UAC (User Account Control) by navigating to Control Panel > User Accounts > Change User Account Control Settings, put it to No notification.  
4. Reset the settings files for Trados Studio and run a repair: https://gateway.sdl.com/apex/communityknowledge?articleName=000001414
 

Corrupted installation.

How to disable UAC (User Account Control):
https://gateway.sdl.com/apex/communityknowledge?articleName=000001373

How to repair the Trados Studio installation:
https://gateway.sdl.com/apex/communityknowledge?articleName=000001414