Project with GWT 2.8.1 configured is trying to launch SuperDevMode with superdevmode-launcher-legacy.jar


This one is really quite confusing. I have 2 clones of my code (different branches, where one is simply a few commits ahead of the other). When I invoke my GWT run config for the "older" it works just fine; when I try on the "newer" I get an error.

The difference, as far as I can tell, is that the "newer" branch is including `plugins/GwtStudio/lib/sdm-launcher/superdevmode-launcher-legacy.jar` (from my IntelliJ IDEA installation) in the classpath. 

I have diffed the .idea/ directories between the two; I have even manually replaced the .idea/runConfigurations directory in the newer with the files from the older.

I cannot see what would possibly be causing this issue.

I would *really* appreciate a pointer on where I could look.

(In the meantime, I've just deleted the plugins/GwtStudio/lib/sdm-launcher/superdevmode-launcher-legacy.jar file from my IJ installation, and so I can get started...)

The other weird issue is that even though all our modules are configured to use language level 8, my GWT code in the newer branch is giving me errors like, "Diamond types are not supported at language level '1.6' (configured by GWT facet)".

I've looked in the GWT facets and confirmed that they all have the path to the GWT installation set to correctly point to my GWT 2.8.1 installation directory. (And yes, I've confirmed that the installation directory really does have a 2.8.1 installation.)

Both myself & a coworker are seeing this issue. He's running 2017.2.5 and I'm running the latest EA of 2017.3.





I've asked the responsible developer to comment with more details, but it looks like IntelliJ IDEA has cached the wrong GWT version somewhere and for some reason doesn't understand that you have version 2.8.

You can try to move/rename IDE folders ( to start with the defaults and reconfigure GWT libraries from scratch in the project.


I manually deleted a number of directories under the ~/.IntelliJIDEA2017.3/system directory:

  • stat
  • index
  • frameworks/detection
  • compile-server
  • compiler
  • gwt
  • caches

I'm sure not everything in that list had to be deleted, but it cleared things up.

I'm hopeful that this will also unblock my co-worker.



I had a similar problem ("Diamond types are not supported at language level '1.6' (configured by GWT facet)") running version 2017.3.5.

Deleting the contents of ~/.IntelliJIDEA2017.3/system/gwt and restarting IDEA fixed it.


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