In this article, we will explain how to resolve the below error:




I am trying to deploy new JSON file in the NiFi directory after that I am getting below NiFi server down issue and we provided simple resolution for that.

Error: NiFi server down

ERROR [Timer-Driven Process Thread-9] o.a.nifi.processors.standard.SplitJson SplitJson[id= ] SplitJson[id= ] failed to process due to java.lang.IllegalArgumentException: root can not be null; rolling back session: {}
java.lang.IllegalArgumentException: root can not be null
at com.jayway.jsonpath.internal.Utils.notNull(Utils.java:213)
at com.jayway.jsonpath.internal.token.EvaluationContextImpl.<init>(EvaluationContextImpl.java:58)
at com.jayway.jsonpath.internal.CompiledPath.evaluate(CompiledPath.java:50)
at com.jayway.jsonpath.internal.CompiledPath.evaluate(CompiledPath.java:61)
at com.jayway.jsonpath.JsonPath.read(JsonPath.java:178)
at com.jayway.jsonpath.internal.JsonReader.read(JsonReader.java:146)
at org.apache.nifi.processors.standard.SplitJson.onTrigger(SplitJson.java:195)
at org.apache.nifi.processor.AbstractProcessor.onTrigger(AbstractProcessor.java:27)
at org.apache.nifi.controller.StandardProcessorNode.onTrigger(StandardProcessorNode.java:1124)
at org.apache.nifi.controller.tasks.ContinuallyRunProcessorTask.call(ContinuallyRunProcessorTask.java:147)
at org.apache.nifi.controller.tasks.ContinuallyRunProcessorTask.call(ContinuallyRunProcessorTask.java:47)
at org.apache.nifi.controller.scheduling.TimerDrivenSchedulingAgent$1.run(TimerDrivenSchedulingAgent.java:128)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
2020-12-21 06:00:20,849 ERROR [Timer-Driven Process Thread-9] o.a.nifi.processors.standard.SplitJson SplitJson[id= ] SplitJson[id= ] failed to process session due to java.lang.IllegalArgumentException: root can not be null: {}
java.lang.IllegalArgumentException: root can not be null
at com.jayway.jsonpath.internal.Utils.notNull(Utils.java:213)
at com.jayway.jsonpath.internal.token.EvaluationContextImpl.<init>(EvaluationContextImpl.java:58)
at com.jayway.jsonpath.internal.CompiledPath.evaluate(CompiledPath.java:50)
at com.jayway.jsonpath.internal.CompiledPath.evaluate(CompiledPath.java:61)
at com.jayway.jsonpath.JsonPath.read(JsonPath.java:178)
at com.jayway.jsonpath.internal.JsonReader.read(JsonReader.java:146)
at org.apache.nifi.processors.standard.SplitJson.onTrigger(SplitJson.java:195)
at org.apache.nifi.processor.AbstractProcessor.onTrigger(AbstractProcessor.java:27)
at org.apache.nifi.controller.StandardProcessorNode.onTrigger(StandardProcessorNode.java:1124)
at org.apache.nifi.controller.tasks.ContinuallyRunProcessorTask.call(ContinuallyRunProcessorTask.java:147)
at org.apache.nifi.controller.tasks.ContinuallyRunProcessorTask.call(ContinuallyRunProcessorTask.java:47)
at org.apache.nifi.controller.scheduling.TimerDrivenSchedulingAgent$1.run(TimerDrivenSchedulingAgent.java:128)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
nifi-app.log

Solution:

Here we provided simple resolution for this error.

Step 1: First, run the Apache NiFi server through with root user. Using below highlighted commands through CLI.

Step 2: Go to the below path (NiFi installed directory)

cd /etc/nifi/bin/

Note: Some of the nifi installation directories are different.

 cd /nifi/conf/

After that check the NiFi shell file is available  in the bin or conf directory.
Step 3: If NiFi shall file is available then run the below command:

./nifi.sh or sh nifi.sh

Resolution 2:

Step 1: Login Ambari web-ui with admin credentials .

Step 2: Then go to NiFi services after that start NiFi service.

Step 3: Wait for 5 mins, it will take some time. After that it will running fine from my end.

Summary: The above error is very common in Cloudera or Hortonworks cluster for NiFi server in the Big Data environment. Basically, Hadoop admin will resolve this error in the NiFi.