Troubleshooting build path issue in Eclipse

source/langdev/meta/lang/stratego/incremental-compilation.rst

@@ -19,8 +19,19 @@ Your file most likely said nothing of the ``build``, meaning it was on the ``bat
 
 .. code:: esv
 
-	provider: target/metaborg/stratego.jar
+  provider: target/metaborg/stratego.jar
 
 Note that a clean build using this setting is necessary at first. It will likely take significantly longer than a clean build using the ``ctree`` format. All subsequent builds should be faster. 
 
 As of Spoofax 2.5.7, there are no known limitations to the incremental compilation setting.
+
+Troubleshooting
+~~~~~~~~~~~~~~~
+
+**Eclipse specific "strategy is undefined" issue:** If your project was generated by a Spoofax 2.5.11 or older, the project build path may not be up to date any more. This will result in errors where the compiled strategies are not found. These errors may look like so:
+
+.. code:: text
+
+  Caused by: org.metaborg.core.MetaborgException: Invoking Stratego strategy editor-outline failed, strategy is undefined
+
+This error would show up once you open an editor for your language once you've built your language with the jar format instead of the ctree format. The solution to the problem is to add the ``src-gen/java`` directory to the build path in Eclipse. You can do this in the Package Explorer by right-clicking the ``src-gen/java`` directory, selecting "Build Path", then selecting "Use as Source Folder". Then clean, rebuild, and strategies should resolve again.