[Trouble Shooting] The project cannot be built until the build path errors are resolved.

[Trouble Shooting]

The project cannot be built until the build path errors are resolved. 

[Solution]

The resolution was to force a resave of the selected projects (and their .classpath files):

1. Open the project properties
2. Select Java Build Path > Libraries
3. Add a new, arbitrary library (to be deleted later) > OK
4. Wait for the workspace to refresh (or force a refresh of the project)
5. The error(s) will go away
6. Remove the dummy library

The only other references I could find were to make minor alterations of contents of the .classpath file.