VSTO Installation Errors


“The following solution cannot be loaded because the .NET Framework 5.5 is not installed Merlin.vsto” when opening Excel after installation.


Locate the folder:

C:\Program Files(x86)\Common Files\Microsoft shared\VSTO\10.0

Where 10 is the Excel version number so may be different on your pc

Rename the file VSTOInstaller.exe.Config   to VSTOInstaller.exe.Config.old


See https://support.microsoft.com/en-gb/help/3176961/cannot-install-vsto-add-in-targeting-net-framework-3-5-to-office-2013


When you click on the MerlinXL vsto installation link you get the error
Exception reading manifest from


Old and out of date .NET version on the the client pc.
Old or out of date VSTO office runtime
The Security Certificated from Thawte used to sign the code was created using .NET4.5 which uses a new security algorithm. Unfortunately this algorithm is not support by older versions of .NET !!


Ensure .NET 4.5 is installed on the pc
Download and install VSTO office runtime from here

For Excel 2007 on Merlin v2.x  if the MerlinXL homepage has an alternative 2007 installation link beneath the original vsto link try this. However due to expiration dates on security certificates this can only install  v2.1.0.2 of the vsto.
If there is no link contact Support@MerlinXL.com to arrange for the alternative 2007 installation to be set up on your server


The following error message is displayed when trying to install the vsto addin

The following Microsoft Office solution cannot be installed due to a general installer error:


The Windows Application log is full


Clear the Windows Application log

Ensure the Application log Property Overwrite as required is checked

Start -> Run -> Eventvwr -> Right click on Application and select Properties




The vsto will not install and the following error message is displayed


Try reinstalling Office 2010 VSTO Runtime


When installing the vsto addin it fails with the following error
Strong name signature not valid for this assembly stdole.dll


The Choose a String name key file has not been set in Visual Studio when the project is published


Developers: Choose a pfx file that does not have a password and republish


During the vsto installation you receive this error message


A corrupted or out of date VSTOInstaller.exe.config file


Locate the VSTOInstaller.exe.config file and rename it with suffix.old

This file is located in

C:\Program Files (x86)\Common Files\microsoft shared\VSTO\10.0

Then try the installation again


During installation of the VSTO you receive this error message

The referenced assembly is not installed on your system (Exception from HRESULT:


Possibly a Corrupt App store in your personal profile


Rename the 2.0 folder at this location and try again

%userprofile%\Local Settings\Apps\2.0″

e.g.: C:\Users\username\Local\AppData\Apps\2.0


When clicking on the MerlinXL.vsto link on the MerlinXL install page an error appears warning that:

There was an error during installation

Downloading file:///………..MerlinXL.dll.manifest did not succeed


1. You tried to install from a browser other than Internet Explorer/Edge (Microsoft !)

2. You saved the link to your pc first  rather than clicking on the link in the webpage  to install.

You mustn’t download the install file first. The “Click-Once” installation process installs other files from the same server location. If the .vsto is downloaded first the installation process does not know where to get the other files from.


Click on the .vsto link in Internet Explorer


Error when installing the VSTO

Specified argument was out of the range of valid values.


Delete the folder:
e.g.  C:\Users\simon\AppData\Local\Apps\2.0
You may need to reboot the pc first if the folder is “in Use”


Unable to install this application because an application with the same identity is already installed
When installing or re-installing the MerlinXL vsto addin you may receive an error message:
Error Message
Unable to install this application because an application with the same identity is already installed. To install this application, either modify the manifest version for this application or uninstall the preexisting application.”

The Microsoft Office Error suggests using Add or Remove programs in the Control Panel, but typically this will already have been done.
This error is probably caused by the Add/Remove Programs operation not removing the items from the registry correctly.


There is already a version of MerlinXL installed

  1. Either check that the COM Addin in Excel is enabled
  2. Uninstall the current version.

Usually a MerlinXL COM addin will automatically update itself is a new version of the addin is placed on the same server that the addin was originally installed from.

Check whether the COM addin is enabled

In Excel check to see if the Merlin tab appears in the Excel ribbon.

If it does and you wish to upgrade then goto the De-install MerlinXL section below, otherwise

Select File | Options | Addin-ins

Select COM- Addins | Go   from the Manage drop down at the bottom of the Options form

In the list of available COM-Addins check the MerlinXL option, then select OK

If the Merlin tab does not appear in the ribbon or MerlinXL is not an available Add-in then goto De-install MerlinXL


De-install MerlinXL

Open Control Panel | Add Remove Programs

If MerlinXL exists, uninstall it by selecting it in the list and then selecting the Uninstall option.

If MerlinXL does not appear as an installed program you need to Clean the Registry

Clean Registry

If it is not there, a previous installation did not uninstall correctly so you need to clear a registry setting.

Open the registry (you will need to have local admin rights)
Delete the registry entries {GUID} relating to MerlinXL
(note it is VSTA not VSTO for some reason)

Additional solutions:
  • Sometimes it may also be necessary to run the following in a cmd.exe window.
    C:> rundll32 dfshim CleanOnlineAppCache


  • Rename the folder 2.0 at the following location. The 2.0 folder will be recreated when you reinstall MerlinXL again. (Note this may affect other VSTO installations)
    •            C:\Users\\AppData\Local\Apps\2.0

Error Message when clicking on the VSTO
Deployment and Application do not have matching security zones


You will get this error message if you opened the MerlinXL webpage using Chrome or Firefox.
You MUST open the MerlinXL webpage using Internet Edge
If you switch to Internet Edge and you still get this error message you should deinstall the MerlinXL vsto from the Control Panel – Programs and Features section, then try installing again.


When clicking on the vsto install link


1. Log on to the pc as an administrator

2. Locate the file UsrClass.dat  in C:\Documents and Settings\user\Local Settings\Application Data\Microsoft\Windows

3. Rename the file UsrClass.dat to UsrClassOld.dat (effectively deleting but with a backup)

4. Log on with your usual username.

5. Try the MerlinXL installation again


When selecting the vsto installation link you get the following error message


The location of the MerlinXL webservice needs to be added to the trusted locations of your browser.


Solution 1
1. Open a web browser

2. Select Tools | Internet Options

3. Select the Security tab

4. Select Trusted Sites

5. Enter the location of your webserver

6. Select Add and then Close

7. Try the MerlinXL installation again

Solution 2. If Solution 1 does not resolve the issue

1. Download the setup.exe file – add /install/setup.exe to the url of the install page
2. Right-click on the setup.exe in file explorer, and select Properties
3. In the Digital Signatures tab select the MerlinXL Ltd Signature
4. Select Details
5. Select View Certificate
6. Select Install Certificate
7. Select Current User then Next
8. Select the option: Place all certificates in the following store, then Browse
9. Select the Trusted Publishers store location, then OK
10. Select Next
11. Restart the browser (Edge or Explorer) and retry in the installation

Error Messages


When selecting the Metadata button in the Wizard Manager to rebuild the application’s metadata an error is displayed

Unable to create the metadata file. Server is disabled for the application



Extend the Security rights of the Merlin Admin User by giving it the role “Shared Services – Financial Management Manager

Applies to versions of MerlinXL designed to run on Excel 2003.

Error Message

When opening older versions of MerlinXL  in a 64 bit OS you see the error message:

Compile error in hidden module

Example Error Message


This error is generally caused by an out of date version of MSCOMCTL.OCX

This file can be found in C:\Windows\SysWOW64

File dates before June 2012 are out of date and should be updated:



Use Excel 2010 or later.

Excel 2007 or earlier is no longer supported

Upgrade the version of MerlinXL to v2



Old Solution

Solution – Requires Local pc admin rights

1. Locate a pc in your organisation that does have an up-to-date  version of the OCX file:

C:\Windows\SysWOW64\MSCOMCTL.OCX dated on or after June 2012.

2. Copy this file and transfer it to the desktop of the affected pc

3. On the affected pc ensure Excel is closed and open CMD.exe (Run as administrator)

4. Unregister the existing OCX file using:

C:> regsvr32.exe /u C:\Windows\sysWOW64\MSCOMCTL.OCX

5. In File Explorer rename the file to  C:\Windows\SysWOW64\MSCOMCTL.OCX.OLD

6. Copy the new ocx file from the desktop to the C:\Windows\SysWOW64 folder

7. In the cmd window reregister the ocx file with:

C:> regsvr32.exe C:\Windows\sysWOW64\MSCOMCTL.OCX

Open MerlinXL and check that the problem is resolved.

If you receive the error message:

Could not load an object because it is not available on this machine


There have been 2 Microsoft Security updates that have caused problems with Excel.

The steps we have found to fix the problems casued by these Security Updates are:

1. If Excel 2007 run the Excel Diagnostics

Ensure Excel is closed before steps 2 & 3

2. Remove the *.exd files (temp files that handle controls)

1. Open a command prompt (DOS Window) with admin rights (right-click – Run As Administrator)

2. Navigate to the Documents and Settings folder    C:\Documents and Settings> (C:\Users  on Windows 7)

3. Enter the following:   C:\Documents and Settings> del/S/A:H/A:-H *.exd  (and press enter)

3. Reregister the MSCOMCTL.OCX file

1. Open the Command Prompt (DOS Window) with admin rights (right-click – Run As Administrator)

2. Type regsvr32.exe /u C:\Windows\System32\MSCOMCTL.OCX

3. Then Type regsvr32.exe C:\Windows\System32\MSCOMCTL.OCX


If this does not fix the issue please contact support@merlinxl.com


This error is as a result of Microsoft security update MS27-027 released May 2012.

Unfortunately this update does not correctly update certain Office dll files, mainly MSCOMCTL.OCX which is used by Excel to display controls on the forms, for example the treeview control used to display the list of Entities.


Delete all *.exd files on the C:\Drive

1. Open a command prompt (DOS Window)

2. Navigate to the Documents and Settings folder    C:\Documents and Settings> (C:\Users  on Windows 7)

3. Enter the following:   C:\Documents and Settings> del/S/A:H/A:-H *.exd  (and press enter)

Alternatively manually locate and delete the following:

a) C:\ Documents and Settings\\Application Data\Microsoft\Data Forms\*.exd

b)  C:\Documents and settings\username\AppData\Loca\\Temp|VBE\*.exd

If this does not fix the issue please contact  support@merlinxl.com

Further Information


The error may also say This Module instead of frmTreeView


This is related to the Microsoft Security Update MS12-027.

Delete “.EXD” files in the local drive, C:\

  1. Open the command prompt
  2. Navigate to Documents and Settings  (or Users on Windows 7)

C:\Documents and Settings> del/S/A:H/A:-H *.EXD (and press enter key)

Depending on your operating system this may be

C:\Users> del/S/A:H/A:-H *.EXD (and press enter key)

Check to see if this has fixed the issue.

If not upgrade to the latest version of the Report Wizard/ Data Wizard.

If the error occurs contact support@merlinxl.com


This error is as a result of Microsoft Security update MS12-060  released August 2012

This update has caused a problem with an Office dll file  MSCOMCTL.OCX used by Excel to display controls in forms.


Re-register the MSCOMCTL.OCX file.

1. Open the Command Prompt (DOS Window) with admin rights (right-click – Run As Administrator)

2. Type the following:

regsvr32.exe /u C:\Windows\System32\MSCOMCTL.OCX

hit Enter

3. Then Type

regsvr32.exe C:\Windows\System32\MSCOMCTL.OCX

hit Enter


64 bit Operating Systems

You will need to subsitute the system32  folder with sysWOW64 in the above commands

i.e.  regsvr32.exe /u C:\Windows\sysWOW64\MSCOMCTL.OCX

      regsvr32.exe C:\Windows\sysWOW64\MSCOMCTL.OCX


If this does not work you may have to roll-back to an earlier version of the MSCOMCTL.OCX file. Please follow the steps outlined here:



If this still does fix the solution please contact support@merlinxl.com

 Further Information






The numbers in the MerlinXL reports are not displayed in the expected format.

Solution 1

In Excel check  File | Options | Advanced  and ensure  the option “Use system separators” is checked.

Solution 2

In HFM Workspace  check File | Preferences | Consolidation  and ensure that the Decimal separator is set to . (full stop)  and the Thousands separator is set to , (comma)

In Excel when displaying the metadata treeview some of the dimensions do not display correctly.

Incompatible language settings.
Some languages (Turkish for example) are incompatible with the metadata xml file and prevent it from being read correctly.

In Control Panel, Region Settings change the Regional format to English (UK or US).
You may need to reboot the pc or at least restart Excel.


After MerlinXL is installed the Merlin tab does not appear in Excel.


Check the following in Excel File Options:

In Add-Ins

  1. In the Manage Drop-Down ensure that MerlinXL is not in the Disabled Add-ins
  2. In the Manager Drop-Down. If MerlinXL is in COM Addins  ensure that it is ticked

In Trust Center | Trust Center Settings

In the Add-ins:

  1. Ensure that the Disable all Application Add-ins is not checked
  2. Ensure Require Application Add-Ins to be signed by Trusted Publisher is not checked

If you change the Trust Center setting you may need to uninstall MerlinXL in Control Panel | Programs and Features, then reinstall

You should also close Excel and reopen


The MerlinXL forms do not display completely


The PC Display zoom is set to more than 100%

In older versions of MerlinXL the forms do not resize correctly


Select Control Panel | Display

Set the display to 100%

See the recommended solutions for High Resolution monitors



Consider upgrading to the latest version of MerlinXL

The vsto is only automatically updated from the server from which it was originally installed.

If it has not updated when the server is updated with a newer version of MerlinXL it could be because of one of two reasons:
1. The vsto was not installed from the server that has been upgraded.
2. The vsto is not set to update everytime Excel is opened.

To manually update the vsto:
1. Open Control Panel
2. Open Uninstall a Program
3. Locate the MerlinXL application
4. In the bottom of the panel see the “Update Information”


If it is the server listed in the Update Information is the one that has been updated, click on the link to update the vsto from the server
If the Update Information is pointing to a different server, Uninstall the Vsto using the Uninstall button
Open Internet Explorer and enter the Merlin url to the updated server
Install the vsto from the updated server

©2024 Merlinxl. All Rights Reserved.

©2024 Merlinxl. All Rights Reserved.

©2024 Merlinxl. All Rights Reserved.