PowerPivot error: unable to upgrade the Data Model in this workbook

Upon opening a PowerPivot in Excel 2013 workbook, I get the following message:

unable to upgrade the Data Model in this workbook. The error occurred while upgrading PowerPivot workbook. The data model has reverted to the previous version

The PowerPivot model was created in Excel 2013. The machine is 64-bit and the model was created here and hasn’t been moved.
It was working fine yesterday, and the only real change was the addition of a password in order to secure the file.

The error message in details is here:

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Error Message:
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Element not found. (Exception from HRESULT: 0x8002802B (TYPE_E_ELEMENTNOTFOUND))

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Call Stack:
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   at Microsoft.Office.PowerPivot.ExcelAddIn.INativeEntryPoint.BeginUpgradeASPPModel(String workbookName)
   at Microsoft.Office.PowerPivot.ExcelAddIn.InProcServer.LoadSandboxAfterConnection(String errorCache)

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Resolution

I resolved this issue by:
running the ‘PowerPivot in Sharepoint 2013 Configuration’.
I also removed the password from the file. To move it around, I will have to use other methods of encrypting the file.  For customer data, I use diskGenie iStorage portable encrypted hard drives and USBs, rather than the plethora of USBs I tend to pick up for free from events.

After running the Wizard and removing the password, I could open up the PowerPivot model just fine.

Hope that helps.