I installed v2.2.0 and now see messages about such and such module is not found.
Because v2.2.0 finally sheds all the old 1.0 style code, the old 1.0 style modules no longer exist. In some cases, Exponent is still able to display the module because the 2.0 module has the same name, but in this case, the referenced 'hard-coded' module in the theme template(s) (don't forget subthemes) still refers to the old module with the 'module' suffix'. You'll need to update the hard-coded module entries in your theme templates. This article explains how to update your custom theme template(s).