Leslie Vail lets us know that the Update path is back for 9.00.0388 to GP 2010. There were some issues with the new payroll tax update but it’s now possible to update from GP 9 to GP 2010 again.
Dynamics Confessor Blogspot: Update path is back for 9.00.0388 to GP 2010
Microsoft & the GP EcosystemGP 2010GP 9
Archived post from 2011. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.