Processing 4 not working in Python mode with Windows 10

Python mode for Processing 4 installed correctly.

Execution mode with simple instruction gives :

Exception in thread "AWT-EventQueue-0" java.lang.NoSuchMethodError: 'java.lang.String processing.app.Sketch.getMainProgram()'
	at jycessing.mode.run.PdeSketch.<init>(PdeSketch.java:55)
	at jycessing.mode.PyEditor.runSketch(PyEditor.java:348)
	at jycessing.mode.PyEditor.handleRun(PyEditor.java:369)
	at jycessing.mode.PyToolbar.handleRun(PyToolbar.java:22)
	at processing.app.ui.EditorToolbar$1.actionPerformed(EditorToolbar.java:135)
	at processing.app.ui.EditorButton.mousePressed(EditorButton.java:191)
	at java.desktop/java.awt.Component.processMouseEvent(Component.java:6623)
	at java.desktop/javax.swing.JComponent.processMouseEvent(JComponent.java:3389)
	at java.desktop/java.awt.Component.processEvent(Component.java:6391)
	at java.desktop/java.awt.Container.processEvent(Container.java:2266)
	at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:5001)
	at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2324)
	at java.desktop/java.awt.Component.dispatchEvent(Component.java:4833)
	at java.desktop/java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4948)
	at java.desktop/java.awt.LightweightDispatcher.processMouseEvent(Container.java:4572)
	at java.desktop/java.awt.LightweightDispatcher.dispatchEvent(Container.java:4516)
	at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2310)
	at java.desktop/java.awt.Window.dispatchEventImpl(Window.java:2780)
	at java.desktop/java.awt.Component.dispatchEvent(Component.java:4833)
	at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:773)
	at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:722)
	at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:716)
	at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:97)
	at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:746)
	at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:744)
	at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
	at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:743)
	at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
	at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)

Welcome @fransua

Are you using Processing 4.0 beta 6? I’m aware there’s a Python Mode issue with this release. Have you tried Processing 4.0 beta 5?

(If that solves the problem, there’s likely a fix coming in beta 7)

seconding this, was having this exact same error and will return back once I install previous version

Processing 4.0 beta 7 has just released, which rolls back the change that broke Python Mode in 4.0b6.