Adobe AEM Error Resolution

Unable to validate node types since project wknd-sites-guide.ui.apps is not associated with a server or the server is not started

This error occurs at Eclipse IDE. To fix this:

1) Right+Click the wknd-sites-guide.ui.apps project in the Project explorer;

2) Open Properties > Project Facets;

3) Uncheck Dynamic Web Module.

This should resolve the error.