Excel Start-up Errors

Below is a list of the known errors that can occur during Excel start-up.

Cannot Find .xll File

Unless you moved the add-in file yourself, this message is the result of FormulaBoost not being properly installed.

The most likely cause is that the installation path was changed to a folder such as C:\Program Files or C:\Program Files (x86) which requires administrator rights but the installer does not have administrator rights. This resulted in the installation failing part-way through the process. To fix this, the registry key that is telling Excel to load this file when it starts must be removed.

To do that, open your registry and navigate to the following (where '16.0' is replaced with your version of Excel):

In this folder, look for the following entry and delete it. Note that the name OPEN may appear as OPEN1, OPEN2, OPEN3, etc., depending upon how many other Excel add-ins you have installed.

Diagnostic Display Window Error

There are two errors that display a 'Diagnostic Display' dialog when Excel starts-up.

1. "Ribbon/COM add-in could not be registered"

The most likely cause of this message is that Excel has put FormulaBoost in an error state and has disabled it. Re-enabling it solves this problem.

To re-enable FormulaBoost do the following:

  1. Click the File tab, click Options, and then click the Add-Ins
  2. In the Manage box, click Disabled Items, and then click Go
  3. Select FormulaBoost and click Enable then Close

If you do not see FormulaBoost in the list of Disabled Items, please contact support for further assistance.

2. "AutoOpen Error"

This occurs randomly and without a known cause, however in all known cases the add-in continues to function properly.

If you consistently receive this message, please contact support.

FormulaBoost Specific Errors

These are errors that are created and handled specifically by FormulaBoost. These errors prevent the use of the add-in but can be solved by providing the error code to us.

An error of this type is signalled by the FormulaBoost Ribbon showing a 'Read Me' button:

Click the 'Read Me' button to see the error code:

As the dialog indicates, if the error continues, please contact support and provide the error code so we can diagnose the problem.


For anti-virus related issues, visit the anti-virus page.