--- a/mobile/android/tests/browser/robocop/src/org/mozilla/gecko/tests/testBrowserDatabaseHelperUpgrades.java
+++ b/mobile/android/tests/browser/robocop/src/org/mozilla/gecko/tests/testBrowserDatabaseHelperUpgrades.java
@@ -42,16 +42,21 @@ import java.util.ArrayList;
  *   * Copy the current version of the database into (robocop-assets)/browser_db_upgrade/v##.db database. You can do
  * this via Margaret's copy profile addon - take browser.db from the profile directory. This db copy should contain a
  * used profile - e.g. history items, bookmarks. A good way to get a used profile is to sign into sync.
  *   * MAKE SURE YOU COPY YOUR DB FIRST. Then make your changes to the DB schema code.
  *   * Test!
  *   * Note: when the application starts for testing, it may need to upgrade the database from your existing version. If
  * this fails, the application will crash and the test may fail to start.
  *
+ * IMPORTANT:
+ * Test DBs must be created on the oldest version of Android that is currently supported. SQLite
+ * is not forwards compatible. Uploading e.g. a DB created on a 6.0 device will cause failures
+ * when robocop tests running on 4.3 are unable to load it.
+ *
  * Implementation inspired by:
  *   http://riggaroo.co.za/automated-testing-sqlite-database-upgrades-android/
  */
 public class testBrowserDatabaseHelperUpgrades extends UITest {
     private static final int TEST_FROM_VERSION = 27; // We only started testing on this version.
 
     private ArrayList<File> temporaryDbFiles;