Problem loading fastpath in spark 2.5.8 ( successfully loaded in 2.6 beta2)

Hi this is what i get in log after starting spark in the debug mode of course the problem seems to be coming from fastpath but if someone can help it will be great ! thank you .

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Exception in thread “Thread-21” java.lang.ClassCastException: org.jivesoftware.smack.PacketReader$4 cannot be cast to org.jivesoftware.smackx.workgroup.packet.AgentWorkgroups
at org.jivesoftware.smackx.workgroup.agent.Agent.getWorkgroups(Agent.java:49)
at org.jivesoftware.fastpath.FastpathPlugin$1.construct(FastpathPlugin.java:94)
at org.jivesoftware.spark.util.SwingWorker$2.run(SwingWorker.java:129)
at java.lang.Thread.run(Thread.java:619)
18 ao¹t 2009 10:00:44 org.jivesoftware.spark.util.log.Log debug
INFO: Failed to commit to JMFRegistry!