Hi James,
It is a similar problem, basically Form Wizard Pro and mojoPortal both use NeatUpload and they have to use the same version, so whenever I update to a new version of NeatUpload in mojoPortal I also make a new release of Form Wizard Pro that is compatible. But the compatibility goes both ways in that the latest release of Form Wizard Pro requires mojoPortal 2.3.6.4. NeatUpload changes are not very frequent in general but recently there were several changes corresponding to mojoPortal 2.3.6.2 and then to mojoPortal 2.3.6.4, so both required updates for Form Wizard Pro.
See also the release notes for mojoPortal 2.3.6.4 which mentions the new version of Form Wizard Pro, and the System Requirements tab on the Form Wizard Pro product page.
So the short story is upgrading to mojoPortal 2.3.6.4 will solve the error.
Hope it helps,
Joe