AIMMS Knowledge Base Article – KB000060

Error when starting the AIMMS Excel Add-In with Excel 2010


The information in this article applies to:

  • All version of the AIMMS Excel Add-In.
  • Excel 2010.


Starting or installing the AIMMS Excel Add-In on a machine with Excel 2010 installed, may yield an error message, after which you cannot work with the AIMMS Excel Add-In. 


If you have used the AIMMS Excel Add-In with an earlier version of Excel, and upgraded Excel to version 2010, the error message that the AIMMS Excel Add-In might raise, is the following:

Object library invalid or contains references to object definitions that could not be found

The same error message may also appear after installing the Microsoft update for Office 2010 described here.


This error message is caused by an internal caching mechanism for ActiveX components of Excel. Excel has cached the various ActiveX components, used on the forms of the AIMMS Excel Add-In, for performance reasons. This caching takes place in the form of creating various files with the extension .exd in several directories. These .exd-files are not compatible with the current Excel 2010 version, leading to the aforementioned error message upon starting or installing the AIMMS Excel Add-In.


The error message can be removed by first closing Excel 2010 and then deleting the various .exd files. If you want to be sure to remove all .exd files, we recommend to do a Windows search first on your hard disk for files with this extension. If that process takes too long, you might want to look into the following folders:

On Windows XP:

C:\Documents and Settings\[username]\Application Data\Microsoft\Forms

C:\Documents and Settings\[username]\Local Settings\Temp\Excel [version]

C:\Documents and Settings\[username]\Local Settings\Temp\VBE

On Windows Vista/7:




Deleting the .exd files is not harmful in any way: Excel 2010 will automatically create new versions of these files upon running the AIMMS Excel Add-In.

More information

Please see this Microsoft KB article for more information on .exd files.


Last reviewed: 17-04-2012
Keywords: KB000060, AIMMS Excel Add-In Office 2010 Error object library invalid