Hi @mabucz  Any idea why I am getting a java.lang.ClassNotFoundException: SSEStreamClient even though the SSEStreamClient module is successfully loaded and it even logs that line SSEStreamClient: Initialized. I am running that in a NiFi 2.4.0 docker container. 2025-10-02 20:28:26,695 INFO [Monitor Processor Lifecycle Thread-2] o.a.n.c.s.TimerDrivenSchedulingAgent Scheduled StandardStatelessGroupNode[group=StandardProcessGroup[identifier=269832be-6b12-38c0-26df-cf4c47ff2b84,name=event-forwarder]] to run with 1 threads 2025-10-02 20:28:29,148 INFO [Initialize SSEStreamClient] org.apache.nifi.py4j.PythonProcess Successfully created Python Virtual Environment ./work/python/extensions/SSEStreamClient/2.4.0-KPCS 2025-10-02 20:28:29,150 INFO [Initialize SSEStreamClient] org.apache.nifi.py4j.PythonProcess Launching Python Process /opt/nifi/nifi-current/./work/python/extensions/SSEStreamClient/2.4.0-KPCS/bin/python3 /opt/nifi/nifi-current/./python/framework/Controller.py with working directory ./work/python/extensions/SSEStreamClient/2.4.0-KPCS to communicate with Java on Port 35515 2025-10-02 20:28:29,314 INFO [python-log-514] org.apache.nifi.py4j.Controller Listening for requests from Java side using Python Port 37553, communicating with Java on port 35515 2025-10-02 20:28:29,395 INFO [Initialize SSEStreamClient] org.apache.nifi.py4j.PythonProcess Successfully started and pinged Python Server. Python Process = Process[pid=514, exitValue="not exited"] 2025-10-02 20:28:29,541 INFO [python-log-514] python.ExtensionManager Installing dependencies ['-r', '/opt/nifi/nifi-current/python_extensions/SSEStreamProcessor/requirements.txt', 'sseclient-py', 'requests'] for SSEStreamClient to /opt/nifi/nifi-current/./work/python/extensions/SSEStreamClient/2.4.0-KPCS using command ['/opt/nifi/nifi-current/./work/python/extensions/SSEStreamClient/2.4.0-KPCS/bin/python3', '-m', 'pip', 'install', '--no-cache-dir', '--target', '/opt/nifi/nifi-current/./work/python/extensions/SSEStreamClient/2.4.0-KPCS', '-r', '/opt/nifi/nifi-current/python_extensions/SSEStreamProcessor/requirements.txt', 'sseclient-py', 'requests'] 2025-10-02 20:28:29,934 INFO [Checkpoint FlowFile Repository] o.a.n.c.r.WriteAheadFlowFileRepository Initiating checkpoint of FlowFile Repository 2025-10-02 20:28:29,935 INFO [Checkpoint FlowFile Repository] o.a.n.c.r.WriteAheadFlowFileRepository Successfully checkpointed FlowFile Repository with 0 records in 0 milliseconds 2025-10-02 20:28:30,483 INFO [python-log-514] org.apache.nifi.py4j.ProcessLog Collecting sseclient-py 2025-10-02 20:28:30,728 INFO [python-log-514] org.apache.nifi.py4j.ProcessLog Downloading sseclient_py-1.8.0-py2.py3-none-any.whl (8.8 kB) 2025-10-02 20:28:30,843 INFO [python-log-514] org.apache.nifi.py4j.ProcessLog Collecting requests 2025-10-02 20:28:30,869 INFO [python-log-514] org.apache.nifi.py4j.ProcessLog Downloading requests-2.32.5-py3-none-any.whl (64 kB) 2025-10-02 20:28:30,915 INFO [python-log-514] org.apache.nifi.py4j.ProcessLog ???????????????????????????????????????? 64.7/64.7 kB 1.7 MB/s eta 0:00:00 2025-10-02 20:28:31,208 INFO [python-log-514] org.apache.nifi.py4j.ProcessLog Collecting charset_normalizer<4,>=2 2025-10-02 20:28:31,234 INFO [python-log-514] org.apache.nifi.py4j.ProcessLog Downloading charset_normalizer-3.4.3-cp311-cp311-manylinux2014_x86_64.manylinux_2_17_x86_64.manylinux_2_28_x86_64.whl (150 kB) 2025-10-02 20:28:31,270 INFO [python-log-514] org.apache.nifi.py4j.ProcessLog ??????????????????????????????????????? 150.3/150.3 kB 4.4 MB/s eta 0:00:00 2025-10-02 20:28:31,312 INFO [python-log-514] org.apache.nifi.py4j.ProcessLog Collecting idna<4,>=2.5 2025-10-02 20:28:31,336 INFO [python-log-514] org.apache.nifi.py4j.ProcessLog Downloading idna-3.10-py3-none-any.whl (70 kB) 2025-10-02 20:28:31,341 INFO [python-log-514] org.apache.nifi.py4j.ProcessLog ???????????????????????????????????????? 70.4/70.4 kB 18.7 MB/s eta 0:00:00 2025-10-02 20:28:31,415 INFO [python-log-514] org.apache.nifi.py4j.ProcessLog Collecting urllib3<3,>=1.21.1 2025-10-02 20:28:31,456 INFO [python-log-514] org.apache.nifi.py4j.ProcessLog Downloading urllib3-2.5.0-py3-none-any.whl (129 kB) 2025-10-02 20:28:31,460 INFO [python-log-514] org.apache.nifi.py4j.ProcessLog ????????????????????????????????????? 129.8/129.8 kB 250.4 MB/s eta 0:00:00 2025-10-02 20:28:31,537 INFO [python-log-514] org.apache.nifi.py4j.ProcessLog Collecting certifi>=2017.4.17 2025-10-02 20:28:31,571 INFO [python-log-514] org.apache.nifi.py4j.ProcessLog Downloading certifi-2025.8.3-py3-none-any.whl (161 kB) 2025-10-02 20:28:31,579 INFO [python-log-514] org.apache.nifi.py4j.ProcessLog ?????????????????????????????????????? 161.2/161.2 kB 93.2 MB/s eta 0:00:00 2025-10-02 20:28:31,684 INFO [python-log-514] org.apache.nifi.py4j.ProcessLog Installing collected packages: sseclient-py, urllib3, idna, charset_normalizer, certifi, requests 2025-10-02 20:28:32,219 INFO [python-log-514] org.apache.nifi.py4j.ProcessLog Successfully installed certifi-2025.8.3 charset_normalizer-3.4.3 idna-3.10 requests-2.32.5 sseclient-py-1.8.0 urllib3-2.5.0 2025-10-02 20:28:32,222 INFO [python-log-514] org.apache.nifi.py4j.ProcessLog WARNING: Target directory /opt/nifi/nifi-current/work/python/extensions/SSEStreamClient/2.4.0-KPCS/bin already exists. Specify --upgrade to force replacement. 2025-10-02 20:28:32,339 INFO [python-log-514] python.ExtensionManager Successfully installed requirements for SSEStreamClient to /opt/nifi/nifi-current/./work/python/extensions/SSEStreamClient/2.4.0-KPCS 2025-10-02 20:28:32,339 INFO [Initialize Python Processor c7d879e8-97fa-3ad6-e00b-0582b78adde7 (SSEStreamClient)] o.a.n.py4j.StandardPythonProcessorBridge Successfully downloaded dependencies for Python Processor c7d879e8-97fa-3ad6-e00b-0582b78adde7 (SSEStreamClient) 2025-10-02 20:28:32,433 INFO [python-log-514] python.ExtensionManager Loaded module SSEStreamClient 2025-10-02 20:28:32,436 INFO [python-log-514] SSEStreamClient SSEStreamClient: Initialized. 2025-10-02 20:28:32,457 INFO [Initialize Python Processor c7d879e8-97fa-3ad6-e00b-0582b78adde7 (SSEStreamClient)] o.a.n.py4j.StandardPythonProcessorBridge Successfully loaded Python Processor c7d879e8-97fa-3ad6-e00b-0582b78adde7 (SSEStreamClient) ------------------------- 2025-10-02 20:28:36,428 INFO [Monitor Processor Lifecycle Thread-1] o.a.n.stateless.engine.ComponentBuilder Created Processor of type org.apache.nifi.processors.standard.LogAttribute with identifier fe0cfbf3-c27f-36ae-a4ac-3a9c1b016fab 2025-10-02 20:28:36,429 INFO [Monitor Processor Lifecycle Thread-1] o.a.nifi.groups.StandardProcessGroup LogAttribute[id=fe0cfbf3-c27f-36ae-a4ac-3a9c1b016fab] added to StandardProcessGroup[identifier=af74d24b-16e6-3044-b8a1-41f31c182d6c,name=app] 2025-10-02 20:28:36,430 INFO [Monitor Processor Lifecycle Thread-1] o.a.n.f.s.StandardVersionedComponentSynchronizer Added LogAttribute[id=fe0cfbf3-c27f-36ae-a4ac-3a9c1b016fab] to StandardProcessGroup[identifier=af74d24b-16e6-3044-b8a1-41f31c182d6c,name=app] 2025-10-02 20:28:36,430 INFO [Monitor Processor Lifecycle Thread-1] o.a.n.stateless.engine.ComponentBuilder Created Processor of type org.apache.nifi.processors.standard.EvaluateJsonPath with identifier 1c3a7a3c-70d9-3165-c78a-4d4ea1353920 2025-10-02 20:28:36,431 INFO [Monitor Processor Lifecycle Thread-1] o.a.nifi.groups.StandardProcessGroup EvaluateJsonPath[id=1c3a7a3c-70d9-3165-c78a-4d4ea1353920] added to StandardProcessGroup[identifier=af74d24b-16e6-3044-b8a1-41f31c182d6c,name=app] 2025-10-02 20:28:36,431 INFO [Monitor Processor Lifecycle Thread-1] o.a.n.f.s.StandardVersionedComponentSynchronizer Added EvaluateJsonPath[id=1c3a7a3c-70d9-3165-c78a-4d4ea1353920] to StandardProcessGroup[identifier=af74d24b-16e6-3044-b8a1-41f31c182d6c,name=app] 2025-10-02 20:28:36,432 ERROR [Monitor Processor Lifecycle Thread-1] o.a.n.groups.StandardStatelessGroupNode StandardStatelessGroupNode[group=StandardProcessGroup[identifier=af74d24b-16e6-3044-b8a1-41f31c182d6c,name=app]] Failed to start StandardStatelessGroupNode[group=StandardProcessGroup[identifier=af74d24b-16e6-3044-b8a1-41f31c182d6c,name=app]]; will try again in 10 seconds java.lang.IllegalStateException: Could not create Processor of type SSEStreamClient at org.apache.nifi.stateless.engine.StatelessFlowManager.createProcessor(StatelessFlowManager.java:197) at org.apache.nifi.controller.flow.AbstractFlowManager.createProcessor(AbstractFlowManager.java:428) at org.apache.nifi.flow.synchronization.StandardVersionedComponentSynchronizer.addProcessor(StandardVersionedComponentSynchronizer.java:2654) at org.apache.nifi.flow.synchronization.StandardVersionedComponentSynchronizer.synchronizeProcessors(StandardVersionedComponentSynchronizer.java:1197) at org.apache.nifi.flow.synchronization.StandardVersionedComponentSynchronizer.synchronize(StandardVersionedComponentSynchronizer.java:601) at org.apache.nifi.flow.synchronization.StandardVersionedComponentSynchronizer.lambda$synchronize$10(StandardVersionedComponentSynchronizer.java:393) at org.apache.nifi.controller.flow.AbstractFlowManager.withParameterContextResolution(AbstractFlowManager.java:668) at org.apache.nifi.flow.synchronization.StandardVersionedComponentSynchronizer.synchronize(StandardVersionedComponentSynchronizer.java:388) at org.apache.nifi.groups.StandardProcessGroup.synchronizeFlow(StandardProcessGroup.java:3881) at org.apache.nifi.controller.flow.StandardStatelessGroupNodeFactory.createStatelessProcessGroup(StandardStatelessGroupNodeFactory.java:296) at org.apache.nifi.controller.flow.StandardStatelessGroupNodeFactory$1.createStatelessProcessGroup(StandardStatelessGroupNodeFactory.java:153) at org.apache.nifi.groups.StandardStatelessGroupNode.createStatelessFlow(StandardStatelessGroupNode.java:345) at org.apache.nifi.groups.StandardStatelessGroupNode.initialize(StandardStatelessGroupNode.java:218) at org.apache.nifi.groups.StandardStatelessGroupNode.lambda$initialize$1(StandardStatelessGroupNode.java:246) at org.apache.nifi.engine.FlowEngine.lambda$wrap$1(FlowEngine.java:105) at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:572) at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317) at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304) at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144) at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642) at java.base/java.lang.Thread.run(Thread.java:1583) Caused by: org.apache.nifi.controller.exception.ProcessorInstantiationException: SSEStreamClient at org.apache.nifi.stateless.engine.ComponentBuilder.createLoggableProcessor(ComponentBuilder.java:319) at org.apache.nifi.stateless.engine.ComponentBuilder.buildProcessor(ComponentBuilder.java:131) at org.apache.nifi.stateless.engine.StatelessFlowManager.createProcessor(StatelessFlowManager.java:173) ... 20 common frames omitted Caused by: java.lang.ClassNotFoundException: SSEStreamClient ... 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