Close the error message and follow these steps:

1. Go to (you can copy/paste this path in File Explorer in Windows OS):
- for Trados Studio 2017: C:\Users\%USERNAME%\AppData\Roaming\SDL\SDL Trados Studio\14
- for Trados Studio 2019: C:\Users\%USERNAME%\AppData\Roaming\SDL\SDL Trados Studio\15
- for Trados Studio 2021: C:\Users\%USERNAME%\AppData\Roaming\SDL\SDL Trados Studio \16

2. Rename the Plugins folder (for example into Plugins_old)
3. Run a Trados Studio repair (see Repairing your installation of SDL Trados Studio) from Control Panel\Programs\Programs and Features (optional)
4. Restart Trados Studio

If the issue persists, please also go to:
- for Trados Studio 2017:  C:\ProgramData\SDL\SDL Trados Studio\14 
- for Trados Studio 2019:  C:\ProgramData\SDL\SDL Trados Studio\15
- for Trados Studio 2021   C:\ProgramData\SDL\SDL Trados Studio\16 
and rename the Plugins folder (for example into Plugins_old)

or go to  Trados Studio 2021: C:\Users\%USERNAME%\AppData\Local\SDL\SDL Trados Studio \ and rename 16 folder to 16_old