Minifi startup fails with "Cannot invoke "org.apache.nifi.flow.VersionedProcessGroup.getIdentifier()" because "rootGroup" is null"

Question

Hello,I have exported the json in nifi and renamed it to flow.json.raw, but when I try to start minifi, I get the error like this:This is my flow in nifiAnd this is my json content：{  "externalControllerServices": {  },  "flowContents": {    "comments": "",    "componentType": "PROCESS_GROUP",    "connections": [      {        "backPressureDataSizeThreshold": "1 GB",        "backPressureObjectThreshold": 10000,        "bends": [],        "componentType": "CONNECTION",        "destination": {          "groupId": "4d2e3379-5165-32b0-bf2a-cc36a354aa29",          "id": "8dd0c880-1b12-3097-90a0-5f20d488f88a",          "instanceIdentifier": "846c8039-231d-353b-b87e-aed9f7408030",          "name": "fromMinifi",          "type": "REMOTE_INPUT_PORT"        },        "flowFileExpiration": "0 sec",        "groupIdentifier": "cad6891f-5564-3a61-8a99-bb7be344adc8",        "identifier": "b0ca1df7-83e8-314b-bb2f-50735ab0ccd2",        "instanceIdentifier": "1e076437-0193-1000-f190-07b262d28ba8",        "labelIndex": 0,        "loadBalanceCompression": "DO_NOT_COMPRESS",        "loadBalanceStrategy": "DO_NOT_LOAD_BALANCE",        "name": "",        "partitioningAttribute": "",        "prioritizers": [],        "selectedRelationships": [          "success"        ],        "source": {          "comments": "",          "groupId": "cad6891f-5564-3a61-8a99-bb7be344adc8",          "id": "39db7913-b310-3485-95fe-6e6e33b1dda8",          "instanceIdentifier": "1b72dcd3-0193-1000-4444-cbda1bf29306",          "name": "GenerateFlowFile",          "type": "PROCESSOR"        },        "zIndex": 0      }    ],    "controllerServices": [],    "defaultBackPressureDataSizeThreshold": "1 GB",    "defaultBackPressureObjectThreshold": 10000,    "defaultFlowFileExpiration": "0 sec",    "executionEngine": "INHERITED",    "flowFileConcurrency": "UNBOUNDED",    "flowFileOutboundPolicy": "STREAM_WHEN_AVAILABLE",    "funnels": [],    "identifier": "cad6891f-5564-3a61-8a99-bb7be344adc8",    "inputPorts": [],    "instanceIdentifier": "1e055241-0193-1000-bfce-60069091b1f0",    "labels": [],    "maxConcurrentTasks": 1,    "name": "Mnificonf",    "outputPorts": [],    "position": {      "x": -904,      "y": 16    },    "processGroups": [],    "processors": [      {        "autoTerminatedRelationships": [],        "backoffMechanism": "PENALIZE_FLOWFILE",        "bulletinLevel": "WARN",        "bundle": {          "artifact": "nifi-standard-nar",          "group": "org.apache.nifi",          "version": "2.0.0"        },        "comments": "",        "componentType": "PROCESSOR",        "concurrentlySchedulableTaskCount": 1,        "executionNode": "ALL",        "groupIdentifier": "cad6891f-5564-3a61-8a99-bb7be344adc8",        "identifier": "39db7913-b310-3485-95fe-6e6e33b1dda8",        "instanceIdentifier": "1b72dcd3-0193-1000-4444-cbda1bf29306",        "maxBackoffPeriod": "10 mins",        "name": "GenerateFlowFile",        "penaltyDuration": "30 sec",        "position": {          "x": -888,          "y": 24        },        "properties": {          "character-set": "UTF-8",          "File Size": "1000B",          "Batch Size": "1",          "Unique FlowFiles": "false",          "Data Format": "Text"        },        "propertyDescriptors": {          "character-set": {            "displayName": "Character Set",            "dynamic": false,            "identifiesControllerService": false,            "name": "character-set",            "sensitive": false          },          "File Size": {            "displayName": "File Size",            "dynamic": false,            "identifiesControllerService": false,            "name": "File Size",            "sensitive": false          },          "mime-type": {            "displayName": "Mime Type",            "dynamic": false,            "identifiesControllerService": false,            "name": "mime-type",            "sensitive": false          },          "generate-ff-custom-text": {            "displayName": "Custom Text",            "dynamic": false,            "identifiesControllerService": false,            "name": "generate-ff-custom-text",            "sensitive": false          },          "Batch Size": {            "displayName": "Batch Size",            "dynamic": false,            "identifiesControllerService": false,            "name": "Batch Size",            "sensitive": false          },          "Unique FlowFiles": {            "displayName": "Unique FlowFiles",            "dynamic": false,            "identifiesControllerService": false,            "name": "Unique FlowFiles",            "sensitive": false          },          "Data Format": {            "displayName": "Data Format",            "dynamic": false,            "identifiesControllerService": false,            "name": "Data Format",            "sensitive": false          }        },        "retriedRelationships": [],        "retryCount": 10,        "runDurationMillis": 0,        "scheduledState": "ENABLED",        "schedulingPeriod": "5 sec",        "schedulingStrategy": "TIMER_DRIVEN",        "style": {        },        "type": "org.apache.nifi.processors.standard.GenerateFlowFile",        "yieldDuration": "1 sec"      }    ],    "remoteProcessGroups": [      {        "comments": "",        "communicationsTimeout": "30 sec",        "componentType": "REMOTE_PROCESS_GROUP",        "groupIdentifier": "cad6891f-5564-3a61-8a99-bb7be344adc8",        "identifier": "4d2e3379-5165-32b0-bf2a-cc36a354aa29",        "inputPorts": [          {            "batchSize": {            },            "componentType": "REMOTE_INPUT_PORT",            "concurrentlySchedulableTaskCount": 1,            "groupIdentifier": "4d2e3379-5165-32b0-bf2a-cc36a354aa29",            "identifier": "8dd0c880-1b12-3097-90a0-5f20d488f88a",            "instanceIdentifier": "846c8039-231d-353b-b87e-aed9f7408030",            "name": "fromMinifi",            "remoteGroupId": "4d2e3379-5165-32b0-bf2a-cc36a354aa29",            "scheduledState": "ENABLED",            "targetId": "1e06d5ee-0193-1000-88b2-e6a57607a83c",            "useCompression": false          }        ],        "instanceIdentifier": "1b72a1a9-0193-1000-a217-fa7db75fc41a",        "name": "NiFi Flow",        "outputPorts": [],        "position": {          "x": -184,          "y": 0        },        "proxyHost": "",        "proxyUser": "",        "targetUris": "http://10.233.150.213:8443/nifi",        "transportProtocol": "RAW",        "yieldDuration": "10 sec"      }    ],    "scheduledState": "ENABLED",    "statelessFlowTimeout": "1 min"  },  "flowEncodingVersion": "1.0",  "parameterContexts": [],  "parameterProviders": [],  "snapshotMetadata": {    "author": "anonymous",    "comments": "",    "timestamp": 1731375780091,    "version": 1  } I hope someone can help me

MattWho · Accepted Answer

@ZNFY

Since you are exporting a flow definition of a process group, you'll need to utilize the MiNiFi toolkit to transform it in to the proper format that can be loaded by MiNiFi. The MiNiFi-toolkit can be downloaded from here: https://nifi.apache.org/download/ (select "MINIFI' and click download link for Toolkit). Execute:

./minifi-toolkit/bin/config.sh transform-nifi <exported flow definition> flow.json.raw

Now edit the flow.json.raw file and edit the following property at start of file (value can not be 0.)

"maxTimerDrivenThreadCount":5

Now you can start your MiNiFi and it will create the flow.json.gz as it starts.

Please help our community thrive. If you found any of the suggestions/solutions provided helped you with solving your issue or answering your question, please take a moment to login and click "Accept as Solution" on one or more of them that helped.

Thank you,
Matt

VidyaSargur · Answer

@ZNFY, Welcome to our community! To help you get the best possible answer, I have tagged in our NiFi experts @MattWho @SAMSAL who may be able to assist you further.

Please feel free to provide any additional information or details about your query, and we hope that you will find a satisfactory solution to your question.

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