Due to updating the version of Eclipse, KNIME AP 4.7 did bring some big changes to how some community extensions need to be implemented; your custom nodes may have the same issues.
@gab1one posted some details on updating extensions for 4.7 here:
A full log file (including startup messages) may give more information on the possibly broken extension. Assuming an incompatible plugin is the issue, updating the plugin may be the best solution.
Sorry for the trouble here. If you need additional info I hope Gabriel will be able to help. In that spirit I’ve moved this thread to the Node Development category.