Trados Studio is displaying some errors which refer to a plugin installed. The error messages could be related to a corrupt plugin, incompatibility between Trados Studio and the plugin, older versions of the plugin, etc..
The error messages can be different:

Key already exists
Parameter name: Key

Unexpected exception when getting view part instance of view part Subtitling Preview

Solution 1:

The plugin can be uninstalled by following the steps below, depending on your Trados Studio version.

For Trados Studio 2024, 2022, 2021:

1. Go to Welcome view > Add-Ins tab > SDL Appstore > Installed plug-ins
2. Select the plugin in the list and click on the bin icon to uninstall it.

NOTE: The Plugin Management tool can also be accessed directly from C:\Program Files (x86)\SDL\SDL plugin installer and double clicking on the Sdl.Community.SdlPluginInstaller.exe file

For Trados Studio 2019, 2017 and 2015:

1. Open Trados Studio
2. Go to Welcome view
3. Click on Sdl Plugin Management 
4. Choose the Trados Studio version for which you want to remove the plugin
5. Select the plugin and click on Uninstall

NOTE: The Plugin Management tool can also be accessed directly from: C:\Program Files (x86)\SDL\SDL plugin installer and double clicking on the Sdl.Community.SdlPluginInstaller.exe file

Solution 2:

Remove the plugin manually (follow the path where the plugin information is stored):
For Trados Studio 2024:
1. Go to C:\Users\%Username%\AppData\Roaming\Trados\Trados Studio\18\Plugins\Packages
 2. Rename the plugin you want to have removed to plugin_name_old

For Trados Studio 2022:
1. Go to C:\Users\%Username%\AppData\Roaming\Trados\Trados Studio\17\Plugins\Packages
 2. Rename the plugin you want to have removed to plugin_name_old

For Trados Studio 2021:
1. Go to C:\Users\%Username%\AppData\Roaming\SDL\SDL Trados Studio\16\Plugins\Packages
2. Rename the plugin you want to have removed to plugin_name_old 

For SDL Trados Studio 2019:
1. Go to C:\Users\%Username%\AppData\Roaming\SDL\SDL Trados Studio\15\Plugins\Packages
2. Rename the plugin you want to be removed to plugin_name_old 

For SDL Trados Studio 2017:
1.Go to C:\Users\%Username%\AppData\Roaming\SDL\SDL Trados Studio\14\Plugins\Packages
2. Rename the plugin you want to be removed to plugin_name_old 

If the issue persists, please also remove the plugin from:

For Trados Studio 2022:
1. Go to:
C:\Users\%Username%\AppData\Roaming\Trados\Trados Studio\17\Plugins\Unpacked
C:\Users\%Username%\AppData\Local\Trados\Trados Studio\17\Plugins\Packages + Unpacked
C:\ProgramData\Trados\Trados Studio\17\Plugins\Packages + Unpacked
2. Rename the plugin you want to have removed to plugin_name_old

For Trados Studio 2021
1. Go to:
C:\Users\%Username%\AppData\Roaming\SDL\SDL Trados Studio\16\Plugins\Unpacked
C:\Users\%Username%\AppData\Local\SDL\SDL Trados Studio\16\Plugins\Packages+Unpacked
C:\ProgramData\SDL\SDL Trados Studio\16\Plugins
2. Rename the plugin you want to have removed to plugin_name_old