Today I discovered a rather unpleasant change during a migration of SharePoint 2007 to SharePoint 2010.
The customer is still using Office 2007 but is planning on upgrading next year.
In SharePoint 2007 you had Business Data Connectivity (BDC) to bring external data (think back-end systems) into SharePoint and Office. If you configured a field for External Data on a Document Library, you could see and edit the field value inside the Document Information Panel in Office.
After migrating to SharePoint 2010 you get Business Connectivity Services (BCS). This is the successor to BDC focuses on a better integration with SharePoint content. However, some features were discontinued and altered, including the BDC Field Resolver Web Service (/_vti_bin/bdcfieldsresolver.asmx).
In Office 2010 this works a bit different but the result is still the same; you can view and edit values before saving your document to SharePoint.
Unfortunately, Office 2007 is unaware of this and will just report the BCS field in the Document Information Panel, making it required (which we configured in the field settings in SharePoint). Submitting the document won’t work as long as the value is blank, but entering a value won’t resolve because it still assumes the BDC Web Services.
The error you get when entering a value (and validating it) is:
There was an error in the validation code.
Document Information Panel cannot complete this action, because of an error in the form's code.
The following error occurred:
Expected token 'EOF' found 'NUMBER'.
Upgrading to Office 2010 fixes it. No other solutions/workarounds known.