The following below are suggested resolutions for the error: "Unable to set the installed property of the Add-in class" when opening a Excel workpaper inside Engagement or Workpaper Manager.
 

• The Epace addin has become disabled.  If so try and attempt to perform the following below:

• Microsoft Excel 2016 and Higher:

1. Open Excel from outside of Engagement or Workpaper Manager.
2. Click File.
3. Click Options.
4. Click Add-ins.
5. Make sure the Manage drop down menu shows Excel Add-ins.
6. Click Go.
7. Locate the Epace add-in and check the box next to it to make it active. If epace.xla has been moved to the Disabled Items list, the following error will occur: 
   • "Microsoft Excel cannot access the file '[path]\epace.xla'. There are several possible reasons..."
     1. Return to Step 5 above.
     2. Change the Manage drop down menu to Disabled items. 
     3. If epace.xla appears in the select, select it and click Enable, then click Close.
     4. Return to Step 5 above and repeat Steps 5 - 9.
8. Click OK through all remaining menu options and close Excel.
9. Open a Excel workpaper inside the binder.

• If the error persists after completing the above steps, check to confirm if the version of Excel is not a Windows App Store from Microsoft Office Desktop Apps, if this is the case please refer to our article below.
  •  New Microsoft® Windows® 10 computers come with Microsoft® Office Built-in Windows® app resulting in add-in errors in CCH® ProSystem fx® Engagement or Workpaper Manager.

 

• If still encountering the issue then it's possible a third party add-in is either in the Excel Add-ins or in the COM Add-ins could be causing the issue. Try disabling all other add-ins except for Epace in the Excel Add-ins & Pfx.Ribbon.ExcelAddin in the COM Add-ins. We have identified also an erroneous entry in the Microsoft® Windows® registry. 
  • Warning! Before you edit the Windows registry, and for information about how to edit the registry, see Microsoft Knowledge Base article 256986.
    • Description of the Microsoft Windows Registry.

1. Make sure to back up the Windows registry and that you understand how to restore the registry if a problem occurs.
   • Warning! Modifying your system registry incorrectly can lead to Operating System corruption, possibly requiring reformatting and reinstalling the operating system.  It is suggested that your I.T. Administrator or support staff be consulted before modifying any registry entries.
2. On the keyboard press Windows Key+R.
3. Type RegEdit.exe.
4. Press Enter.
5. Locate the following path: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\##.0\Excel\resiliency\addinlist

• Where "##" is the build number for the version of Microsoft Office that's installed.
• Example Microsoft Office 2016:  HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\16.0\Excel\resiliency\addinlist

6. If the below add-ins are listed change the value from "1" to "2" for the following add-ins:
   • CWConnector.xll
   • epace.xla
   • ActiveData for Excel or ActiveDataAddinModule.
     • Please note CCH ActiveData is no longer supported with Wolters Kluwer and is advised to have this add-in disabled.  Removing the add-in from the Excel Add-ins in Excel also should resolve the issue.
7. Reboot the machine. 

• If the installation of Excel is local, then try a different Window profile on the machine. If the new profile works fine with Engagement or Workpaper Manager, then you will need to recreate the original Window profile.