Error message: La référence d'objet n'est pas définie à une instance d'objet

Hello,

I'm trying to translate a pdf document and I keep on getting the above mentioned error message.

I can't confirm any segment nor save the target file.

Thank you for your help!

<SDLErrorDetails time="20-05-21 12:36:26">
  <ErrorMessage>La référence d'objet n'est pas définie à une instance d'un objet.</ErrorMessage>
  <Exception>
    <Type>System.NullReferenceException, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</Type>
    <HelpLink />
    <Source>Sdl.TranslationStudio.Editor</Source>
    <HResult>-2147467261</HResult>
    <StackTrace><![CDATA[   à Sdl.TranslationStudio.Editor.TranslationMemory.TranslationMemoryViewPart.UpdateIcon()
   à Sdl.TranslationStudio.Editor.TranslationMemory.TranslationMemoryViewPart.UpdateTranslationProvider()
   à Sdl.TranslationStudio.Editor.TranslationMemory.TranslationMemoryViewPart.OnActiveDocumentChanged()
   à Sdl.TranslationStudio.Editor.TranslationMemory.TranslationMemoryViewPart.editorService_ActiveDocumentChanged(IDocument document)
   à Sdl.TranslationStudio.Api.Editor.DocumentEventHandler.Invoke(IDocument document)
   à Sdl.TranslationStudio.Editor.EditorService.set_ActiveDocument(IDocument value)
   à Sdl.TranslationStudio.Editor.EditorView.OnActiveViewPartChanged(IViewPartReference viewPartReference)
   à Sdl.Desktop.Platform.AbstractViewWithParts.Control_ActiveViewPartChanged(IViewWithParts view, IViewPartReference viewPartReference)
   à Sdl.Desktop.Platform.WinForms.DockingViewContentControl.OnActiveViewPartChanged(IViewPartReference viewPartReference)
   à Sdl.Desktop.Platform.WinForms.DockingViewContentControl.InternalActivateViewPart(IViewPartReference viewPartToActivate)
   à Sdl.Desktop.Platform.WinForms.DockingViewContentControl._tabControl_SelectedTabChanged(Object sender, SelectedTabChangedEventArgs e)
   à Infragistics.Win.UltraWinTabControl.UltraTabControlBase.OnSelectedTabChanged(SelectedTabChangedEventArgs e)
   à Infragistics.Win.UltraWinTabControl.UltraTabControlBase.RaiseEvent(UltraTabControlEventId id, EventArgs e)
   à Infragistics.Win.UltraWinTabControl.UltraTabControlBase.OnManagerSelectedTabItemChanged(Object sender, SelectedTabItemChangedEventArgs e)
   à Infragistics.Win.UltraWinTabs.TabManager.set_SelectedTabItem(ITabItem value)
   à Infragistics.Win.UltraWinTabControl.UltraTabControlBase.SetSelectedTab(UltraTab tab)
   à Infragistics.Win.UltraWinTabControl.UltraTabControlBase.set_SelectedTab(UltraTab value)
   à Sdl.Desktop.Platform.WinForms.DockingViewContentControl.AddViewPartTab(IViewPartReference viewPartReference)
   à Sdl.Desktop.Platform.WinForms.DockingViewContentControl.AddViewPart(IViewPartReference viewPartReference)
   à Sdl.Desktop.Platform.WinForms.DockingViewContentControl.NotifyViewPartAdded(IViewPartReference viewPartReference)
   à Sdl.Desktop.Platform.AbstractViewWithParts.AddViewPart(IViewPartReference viewPartReference)
   à Sdl.Desktop.Platform.AbstractDockingView.AddViewPart(IViewPartReference viewPartReference)
   à Sdl.TranslationStudio.Editor.EditorView.AddDocumentViewPart(IViewPartReference documentViewPartReference)
   à Sdl.TranslationStudio.Editor.Shared.InternalEditorContext.AddDocumentViewPart(IDocumentViewPart documentViewPart)
   à Sdl.TranslationStudio.Api.Editor.AbstractInternalDocument.AfterLoad(IJob job)]]></StackTrace>
  </Exception>
  <Environment>
    <ProductName>SDL Trados Studio</ProductName>
    <ProductVersion>Studio16</ProductVersion>
    <EntryAssemblyFileVersion>16.1.6.4276</EntryAssemblyFileVersion>
    <OperatingSystem>Microsoft Windows 10 Professionnel</OperatingSystem>
    <ServicePack>NULL</ServicePack>
    <OperatingSystemLanguage>1036</OperatingSystemLanguage>
    <CodePage>1252</CodePage>
    <LoggedOnUser>PEG732B\peg</LoggedOnUser>
    <DotNetFrameWork>4.0.30319.42000</DotNetFrameWork>
    <ComputerName>PEG732B</ComputerName>
    <ConnectedToNetwork>True</ConnectedToNetwork>
    <PhysicalMemory>3122516 MB</PhysicalMemory>
  </Environment>
</SDLErrorDetails>