FAQ Why do I get a 'plug-in was unable to load class' error when I activate a menu or toolbar action?
It is possible to get the following error message on the console:
Could not create action delegate for id: sample.Action Reason: Plug-in sample was unable to load class sample.Action.
The most likely reason is that an exception was thrown in the static initializer for a class declared by the offending plug-in. Check the .log file to see whether that indeed happened. The Eclipse Platform loader will not load a plug-in when exceptions are thrown during the initialization of the Java classes that make up the plug-in. Another common reason for this error is the lack of an appropriate constructor for the class being loaded. Most classes declared in extension points must have a public zero-argument constructor. Check the extension point documentation to see what constructor is required for the classes that you declare in an extension.