I get this generic error when trying to select a Preview file to Browse. 
Trados Studio 2019

What is the cause (workaround)?  

<SDLErrorDetails time="27/05/2021 07:35:09">

  <ErrorMessage>Object reference not set to an instance of an object.</ErrorMessage>

  <Exception>

    <Type>System.NullReferenceException, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</Type>

    <HelpLink />

    <Source>Sdl.TranslationStudio.ProjectManagement</Source>

    <HResult>-2147467261</HResult>

    <StackTrace><![CDATA[   at Sdl.TranslationStudio.ProjectManagement.Settings.FilterAdministratorSettingsCategory.GetFileTypeManager()

   at Sdl.TranslationStudio.ProjectManagement.Settings.StudioFilterAdministratorSettingsCategory.SetFileToPreivew(TextBox fileNameTextBox)

   at Sdl.Desktop.Platform.WinForms.SettingsDialogForm._buttonBrowsePreviewFile_Click(Object sender, EventArgs e)

   at System.Windows.Forms.Control.OnClick(EventArgs e)

   at System.Windows.Forms.Button.OnClick(EventArgs e)

   at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)

   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)

   at System.Windows.Forms.Control.WndProc(Message& m)

   at System.Windows.Forms.ButtonBase.WndProc(Message& m)

   at System.Windows.Forms.Button.WndProc(Message& m)

   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)

   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)

   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)]]></StackTrace>

  </Exception>

  <Environment>

    <ProductName>SDL Trados Studio</ProductName>

    <ProductVersion>15.0.0.0</ProductVersion>

    <EntryAssemblyFileVersion>15.2.8.3007</EntryAssemblyFileVersion>

    <OperatingSystem>Microsoft Windows 10 Pro</OperatingSystem>

    <ServicePack>NULL</ServicePack>

    <OperatingSystemLanguage>2057</OperatingSystemLanguage>

    <CodePage>1252</CodePage>

tyo