Is “NullPointerException” a kind of bug?

Hi,
I am having problem with nullpointerexception error.

I create and utilize a workflow related to deep learning(keras), and suddenly the error occurs in all workflows.

ERROR Keras Network Learner 3:13 Execute failed: (“NullPointerException”): null

What I’m most curious about is that one day the error occurred suddenly, and it still works on other computers.

Please answer what is the cause of this problem and if there is a solution.

Hi @zhddhkdn,

Can you provide a stack trace for the error? You can find it in the KNIME log (View -> Open KNIME log). Also, is there a difference in KNIME versions between the computers?

1 Like

Hi bwilhelm,

Sure,

There is no difference in KNIME versions(version: 4.2.0)

Here is a stack trace for error.

2020-09-24 20:26:03,697 : ERROR : main : : WindowsDefenderExceptionHandler : : : PowerShell command powershell -inputformat none -outputformat text -NonInteractive -Command Get-MpComputerStatus -ErrorAction Stop | select -ExpandProperty AMServiceEnabled did not terminate successfully.
2020-09-24 20:26:03,706 : ERROR : main : : WindowsDefenderExceptionHandler : : : Stderr is:
2020-09-24 20:26:03,707 : ERROR : main : : WindowsDefenderExceptionHandler : : : Get-MpComputerStatus : 쇅遺 硫붿꽌 뱶瑜 떎 뻾 븷 닔 뾾 뒿 땲 떎.
2020-09-24 20:26:03,707 : ERROR : main : : WindowsDefenderExceptionHandler : : : 쐞移 以 :1 臾몄옄:1
2020-09-24 20:26:03,707 : ERROR : main : : WindowsDefenderExceptionHandler : : : + Get-MpComputerStatus -ErrorAction Stop | select -ExpandProperty AMSer …
2020-09-24 20:26:03,707 : ERROR : main : : WindowsDefenderExceptionHandler : : : + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2020-09-24 20:26:03,707 : ERROR : main : : WindowsDefenderExceptionHandler : : : + CategoryInfo : MetadataError: (MSFT_MpComputerStatus:ROOT\Microsoft…pComputerStatus) [Get-MpComputer
2020-09-24 20:26:03,707 : ERROR : main : : WindowsDefenderExceptionHandler : : : Status], CimException
2020-09-24 20:26:03,707 : ERROR : main : : WindowsDefenderExceptionHandler : : : + FullyQualifiedErrorId : MI RESULT 16,Get-MpComputerStatus
2020-09-24 20:26:03,707 : ERROR : main : : WindowsDefenderExceptionHandler : : :
2020-09-24 20:26:48,826 : WARN : ModalContext : : Node : Line Plot (local) : 0:18 : Some columns are ignored: bounds missing.
2020-09-24 20:27:07,535 : ERROR : KNIME-Worker-3-Keras Network Learner 0:13 : : Node : Keras Network Learner : 0:13 : Execute failed: Selected Keras back end ‘Keras (TensorFlow)’ is not available anymore. Please check your local installation.
Details: Installation test for Python back end ‘org.knime.dl.keras.tensorflow.core.DLKerasTensorFlowNetwork’ timed out. Please make sure your Python environment is properly set up and consider increasing the timeout (currently 25000 ms) using the VM option ‘-Dknime.dl.installationtesttimeout=’.
org.knime.core.node.InvalidSettingsException: Selected Keras back end ‘Keras (TensorFlow)’ is not available anymore. Please check your local installation.
Details: Installation test for Python back end ‘org.knime.dl.keras.tensorflow.core.DLKerasTensorFlowNetwork’ timed out. Please make sure your Python environment is properly set up and consider increasing the timeout (currently 25000 ms) using the VM option ‘-Dknime.dl.installationtesttimeout=’.
at org.knime.dl.keras.base.nodes.learner.DLKerasLearnerNodeModel.executeInternal(DLKerasLearnerNodeModel.java:642)
at org.knime.dl.keras.base.nodes.learner.DLKerasLearnerNodeModel.execute(DLKerasLearnerNodeModel.java:303)
at org.knime.core.node.NodeModel.executeModel(NodeModel.java:576)
at org.knime.core.node.Node.invokeFullyNodeModelExecute(Node.java:1236)
at org.knime.core.node.Node.execute(Node.java:1016)
at org.knime.core.node.workflow.NativeNodeContainer.performExecuteNode(NativeNodeContainer.java:558)
at org.knime.core.node.exec.LocalNodeExecutionJob.mainExecute(LocalNodeExecutionJob.java:95)
at org.knime.core.node.workflow.NodeExecutionJob.internalRun(NodeExecutionJob.java:201)
at org.knime.core.node.workflow.NodeExecutionJob.run(NodeExecutionJob.java:117)
at org.knime.core.util.ThreadUtils$RunnableWithContextImpl.runWithContext(ThreadUtils.java:334)
at org.knime.core.util.ThreadUtils$RunnableWithContext.run(ThreadUtils.java:210)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at org.knime.core.util.ThreadPool$MyFuture.run(ThreadPool.java:123)
at org.knime.core.util.ThreadPool$Worker.run(ThreadPool.java:246)

Thank you.