GWT module may need to be recompiled

When you get a popup in GWT with the message “gwt module may need to be recompiled” then probably the *.nocache.js file is outdated.

Delete this file [in Maven it is usually placed in the directory src/main/webapp], run ‘clean package’ again and check whether the issue is fixed.

If so, this issue was caused by the fact that the *.nocache.js file that was newly generated by gwt-maven-plugin was overruled by the one you just deleted.