Unable to open RTC client when using Dynamics NAV

We’ve run into a new scenario with both Windows 10 and Windows 11 where the Dynamics NAV RTC Client won’t open. The root cause appears to be due to Excel and an Office update.

If the Dynamics NAV RTC client won’t open with an error in event viewer Application log similar to:

Application: Microsoft.Dynamics.Nav.Client.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Application: Microsoft.Dynamics.Nav.Client.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.NullReferenceException
   at Microsoft.Dynamics.Nav.Client.WinClientExcelExportService.FindMajorVersion(Microsoft.Win32.RegistryKey)
   at Microsoft.Dynamics.Nav.Client.WinClientExcelExportService.<.ctor>b__8_0(Microsoft.Win32.RegistryKey)
   at Microsoft.Dynamics.Nav.Client.WinClientExcelExportService.FindRegistryKey(Microsoft.Win32.RegistryHive, System.String, System.Action`1<Microsoft.Win32.RegistryKey>)
   at Microsoft.Dynamics.Nav.Client.WinClientExcelExportService.FindFirstRegistryKey(System.String, System.Action`1<Microsoft.Win32.RegistryKey>)
   at Microsoft.Dynamics.Nav.Client.WinClientExcelExportService..ctor(Microsoft.Dynamics.Framework.UI.UISession)
   at Microsoft.Dynamics.Nav.Client.WinClient.NavWinFormsClientSession+<>c.<AddServices>b__22_6(Microsoft.Dynamics.Framework.UI.UISession)
   at Microsoft.Dynamics.Framework.UI.ClientSessionCore.AddUIService(System.Func`2<Microsoft.Dynamics.Framework.UI.UISession,Microsoft.Dynamics.Framework.UI.IUIService>)
   at Microsoft.Dynamics.Nav.Client.WinClient.NavWinFormsClientSession.AddServices()
   at Microsoft.Dynamics.Framework.UI.ClientSessionCore.Prepare()
   at Microsoft.Dynamics.Nav.Client.WinClient.StartWinFormsClient.SetupClientSession()
   at Microsoft.Dynamics.Nav.Client.WinClient.StartWinFormsClient.RunCore()
   at Microsoft.Dynamics.Nav.Client.WinClient.StartWinFormsClient.Run(Boolean)
   at Microsoft.Dynamics.Nav.Client.Program.Main(System.String[])

Then it might be due to an Office update. As a workaround you can fix it in one of two ways:

Solution #1

  1. Run an Online Office repair with all users logged off/apps closed
  2. Reboot the machine

Solution #2

Or, you can manually repair the broken entry here:

  1. Open the Registry Editor (regedit.exe)
  2. Manually insert a (Default) key in Computer\HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\App Paths\excel.exe to point your Excel path (this might be C:\Program Files\Microsoft Office\root\Office16\EXCEL.EXE for example, but may vary depending on installation location)

The root cause

We’re still waiting to hear from Microsoft for a long-term fix, though this will get you by. The root cause likely lies with the Office installer, however a simple repair is all that’s required.

This type of issue will become more and more common as the Dynamics RTC client becomes older.

Looking to move to a more supported version of Business Central? Need help with your upgrades? Speak with us about the upgrade options available to you.

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