Actually, this was working fine until refactoring of code took place. The module had a feature that will check whether the navigated html file is already opened or not. If opened, will navigate to it directly and if not, will find its fileobject, create dataobject and open the file in editor. Since refactoring, it assumes (doesn't check) that html file is already opened and tries to navigate to it. Hence, exception is thrown. Check the code (Line #281, 282); http://kenai.com/projects/nbrcp-kolektiv/sources/incubator/content/nbplugins/trunk/ahrefhyperlink.revamped/src/com/wp/nbguru/ahrefhyperlink/revamped/OpenThreadImpl.java?rev=79