Knowledge Base

Troubleshooting CodeTwo Signatures Add-in for Outlook


You experience problems with the CodeTwo Signatures Add-in for Outlook (the classic COM Add-in), for example you're unable to install or launch it.


You can avoid these problems by using our modern Signatures Web Add-in for Outlook instead. It’s easier to deploy (automatically via Microsoft 365 admin center) and it is an agentless solution (there’s nothing to install by end users, and there are no local library dependencies). See the user’s manual to learn how to deploy it.


Read on to learn about encountered problems, their causes and recommended solutions.

Error while checking Outlook version

You get the following or similar error:

It looks like we could not check your Outlook version or Outlook version is not installed on this device.

This error occurs when we are unable to verify which version of Outlook you are using. This may happen if you don't have any Outlook desktop app installed or if your version is too old. Remember that only Outlook 2013 or later is supported. 

If you have an up to date version of Outlook but still get this error, the problem might be related to limited access to your system registry. Make sure that the Windows account you are using during the installation has read/write permissions to the following registry key:


Microsoft .NET Framework issues

After you install the CodeTwo Signatures Add-in for Outlook and restart your Outlook desktop app, the add-in crashes and you receive the following error message:

'CodeTwo Signatures Add-in for Outlook' has fired an exception.

that includes the following (or similar) details:

Exception Source: Esig365.Outlook.Addin.Adx
Exception Type: System.IO.FileLoadException
Exception Message: Could not load file or assembly 'Microsoft.Office.Interop.Outlook, Version=, Culture=neutral, PublicKeyToken=71e9bce111e9429c' or one of its dependencies. Access is denied.
Exception Target Site: OnAddinInitialize

This error occurs because of issues related to Microsoft .NET Framework.

To fix it, make sure you have the required .NET Framework version installed on your machine (i.e. Microsoft .NET Framework 4.7.1). If no, download it and perform the update. If necessary, uninstall the current version and then reinstall .NET Framework by running the downloaded installation file.

If this does not solve the problem, download the Microsoft .NET Framework Repair Tool and run it on the affected machine. The tool detects and resolves issues with .NET Framework installations. It should also fix the problem with the add-in as well.

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