I have generated a trace file using the following command line:
verifyta -u -t1 -f toto spec.xml q01.q
When I open the trace file (i.e. toto-1.xtr) with the UPPAAL simulator (OPEN
button), I get:
java.lang.NullPointerException
        at com.uppaal.engine.Parser.locationVector(Parser.java:78)
        at com.uppaal.engine.Parser.parseState(Parser.java:69)
        at com.uppaal.engine.Parser.parseXTRTrace(Parser.java:308)
        at z.a(Unknown Source)
        at com.uppaal.gui.simulator.Simulator.h(Unknown Source)
        at com.uppaal.gui.simulator.Simulator.g(Unknown Source)
        at E.actionPerformed(Unknown Source)
        at
javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:19
95)
        at
javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.jav
a:2318)
        at
javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel
.java:387)
        at
javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242
)
        at
javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonL
istener.java:236)
        at
java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:2
72)
        at java.awt.Component.processMouseEvent(Component.java:6038)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3260)
        at java.awt.Component.processEvent(Component.java:5803)
        at java.awt.Container.processEvent(Container.java:2058)
        at java.awt.Component.dispatchEventImpl(Component.java:4410)
        at java.awt.Container.dispatchEventImpl(Container.java:2116)
        at java.awt.Component.dispatchEvent(Component.java:4240)
        at
java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4322
)
        at
java.awt.LightweightDispatcher.processMouseEvent(Container.java:3986)
        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3916)
        at java.awt.Container.dispatchEventImpl(Container.java:2102)
        at java.awt.Window.dispatchEventImpl(Window.java:2429)
        at java.awt.Component.dispatchEvent(Component.java:4240)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
        at
java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThre
ad.java:273)
        at
java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.
java:183)
        at
java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThre
ad.java:173)
        at
java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
        at
java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)

Created an attachment (id=153) [details]
UPPAAL model

Created an attachment (id=154) [details]
Query file - quite basic

Created an attachment (id=155) [details]
Trace file generated by verifyta

I cannot reproduce this problem. I have loaded your model in UPPAAL 4.0.6 and
loaded the XTR file in the simulator. It loads without any errors. I also tried
regenerating the trace, both from inside the GUI and with verifyta. In both
cases I did not have a problem.

Could you please check that you can reproduce the problem with the files
attached to this bug. The problem you describe *could* be triggered when
loading a trace file for a different model than the one currently loaded in the
simulator. Could you please check that this is not the case here.

I've rebooted my machine, restarted UPPAAL, and use the file I provide... and
effectively, it works. Well, I am going to try my best to reproduce this bug!

If after more than a year the bug could not be reproduced, it was certainly due
to a mismatch between the model and the trace. We are planning to tight
together traces and models to avoid this problem in the future.

Revision 3779 contains a work-around to detect trace mismatch.