When opening Quickbooks, launching SmartVault or attempting to run an SDK registration fix for SmartVault you may encounter the error " Xerces c-2_5_0_qb_vc10.dll is missing". This error message will prevent QuickBooks from correctly launching certain Addons including SmartVault.
We're still unsure of all the possible causes for this error, but generally it originates from when a user attempts to upgrade to a newer version of QuickBooks but then decides to abort the installation or roll it back. There may be other causes however.
Xerces c-2_5_0_qb_vc10.dll is not a QuickBooks system file so replacing this file even though it's being requested is not possible.
To resolve this issue you will need to run an repair installation for QuickBooks.
Use the instructions at the following link provided by Intuit: