Back again. The greenfoot-debuglog.txt file show below messages. And actually 'import-cache.xml' file was really missing (I don't know why). I've decided to restart Greenfoot and now everything works fine (the missing import-cache.xml has been created by Greenfoot). Would be fine if everything works fine at first start. Maybe by adding the 'import-cache.xml' into the portable version zip file? Have a nice day¨ Laurent ___________________________ Greenfoot run started: Fri Jun 07 08:54:51 CEST 2019 Greenfoot version: 3.5.4 Java version 1.8.0_202 Virtual machine: Java HotSpot(TM) Client VM 25.202-b08 (Oracle Corporation) Running on: Windows 7 6.1 (x86) Java Home: C:\Libre\Greenfoot-windows-354\Greenfoot\jdk\jre ---- Exception in thread "JavaFX Application Thread" java.lang.NullPointerException at java.awt.EventQueue$3$1.run(EventQueue.java:714) at com.sun.javafx.application.PlatformImpl.lambda$null$177(PlatformImpl.java:295) at java.security.AccessController.doPrivileged(Native Method) at com.sun.javafx.application.PlatformImpl.lambda$runLater$178(PlatformImpl.java:294) at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95) at com.sun.glass.ui.win.WinApplication._runLoop(Native Method) at com.sun.glass.ui.win.WinApplication.lambda$null$152(WinApplication.java:177) at java.lang.Thread.run(Thread.java:748) Opening project: P:\...\1 1559890593984: Listening for JDWP connection on address: javadebug Connected to debug VM via dt_shmem transport... Communication with debug VM fully established. java.io.FileNotFoundException while reading import cache: userhome\greenfoot\import-cache.xml (Le fichier spécifié est introuvable) ====