diff --git a/docs/DeveloperGuide.adoc b/docs/DeveloperGuide.adoc
index fcb733d4..0872941e 100644
--- a/docs/DeveloperGuide.adoc
+++ b/docs/DeveloperGuide.adoc
@@ -54,7 +54,7 @@ the test has passed
 . If the script reports that there is no difference between `actual.txt` and `expected.txt`,
 the test has passed
 
-*Troubleshooting test failures*
+*Troubleshooting*
 
 * Problem: How do I examine the exact differences between `actual.txt` and `expected.txt`? +
 Solution: You can use a diff/merge tool with a GUI e.g. WinMerge (on Windows).
@@ -66,3 +66,8 @@ OSes. Convert the `actual.txt` to the format used by your OS using some https://
 * Problem: Test fails during the very first time. +
 Solution: The output of the very first test run could be slightly different because the program
 creates a new storage file. Tests should pass from the 2nd run onwards.
+
+* Problem: `AddressBook` cannot be run, and `src/` is treated as a normal folder instead of as a `Sources Root`. +
+Solution: This can happen if you've accidentally imported the project as a Gradle project.
+First, disable `"Use auto-import"` in `Settings (Preferences)` > `Build...` > `Build Tools` > `Gradle`.
+Finally, right click on `src/` > `Mark Directory as` > `Sources Root`.
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