# UnsatisfiedLinkError in native method when using JNI

**URL:** <https://forum.inductiveautomation.com/t/unsatisfiedlinkerror-in-native-method-when-using-jni/14782>\
**Category:** Module Development\
**Created:** [July 13, 2017, 1:49pm UTC](https://forum.inductiveautomation.com/t/unsatisfiedlinkerror-in-native-method-when-using-jni/14782 "2017-07-13T13:49:03Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![sjackson](https://avatars.discourse-cdn.com/v4/letter/s/f6c823/32.png) [@sjackson](https://forum.inductiveautomation.com/u/sjackson)\
**Post date:** [July 13, 2017, 1:49pm UTC](https://forum.inductiveautomation.com/t/unsatisfiedlinkerror-in-native-method-when-using-jni/14782/1 "2017-07-13T13:49:03Z")

</div>

I have created a jar file using JNI and loaded the DLL with

```auto
static { System.loadLibrary("fwlibj64"); }

```

When instaling the module I get an “UnsatisfiedLinkError in native method”. I have put the libraries in Ignition/lib and added the following lines to “ignition.conf”. There is no problem loading the library as long as I unload it in shutdown as described in this [post](http://forum.inductiveautomation.com/t/module-using-dll-unloading/6183). but making a call to a method does it in.

Version 7.9.3 (64-bit)

```auto
wrapper.java.classpath.3=lib/Fwlib64.jar
wrapper.java.classpath.4=lib/fwlibj64.dll

```

```auto
 java.lang.UnsatisfiedLinkError: fwlib64.Fwlib64JNI.cnc_allclibhndl3(Ljava/lang/String;II[I)S
 	at fwlib64.Fwlib64JNI.cnc_allclibhndl3(Native Method)
 	at fwlib64.Fwlib64.cnc_allclibhndl3(Fwlib64.java:23)
 	at com.inductiveautomation.ignition.examples.stp.SimpleProviderGatewayHook.getHandle(SimpleProviderGatewayHook.java:177)
 	at com.inductiveautomation.ignition.examples.stp.SimpleProviderGatewayHook.setup(SimpleProviderGatewayHook.java:89)
 	at com.inductiveautomation.ignition.gateway.modules.ModuleManagerImpl$LoadedModule.setup(ModuleManagerImpl.java:2187)
 	at com.inductiveautomation.ignition.gateway.modules.ModuleManagerImpl.startupModule(ModuleManagerImpl.java:1052)
 	at com.inductiveautomation.ignition.gateway.modules.ModuleManagerImpl$2.call(ModuleManagerImpl.java:648)
 	at com.inductiveautomation.ignition.gateway.modules.ModuleManagerImpl.executeModuleOperation(ModuleManagerImpl.java:801)
 	at com.inductiveautomation.ignition.gateway.modules.ModuleManagerImpl.installModuleInternal(ModuleManagerImpl.java:624)
 	at com.inductiveautomation.ignition.gateway.modules.ModuleManagerImpl.access$900(ModuleManagerImpl.java:134)
 	at com.inductiveautomation.ignition.gateway.modules.ModuleManagerImpl$InstallCommand.execute(ModuleManagerImpl.java:1722)
 	at com.inductiveautomation.ignition.gateway.modules.ModuleManagerImpl$Receiver.receiveCall(ModuleManagerImpl.java:1659)
 	at com.inductiveautomation.ignition.gateway.redundancy.QueueableMessageReceiver.receiveCall(QueueableMessageReceiver.java:45)
 	at com.inductiveautomation.ignition.gateway.redundancy.RedundancyManagerImpl.dispatchMessage(RedundancyManagerImpl.java:739)
 	at com.inductiveautomation.ignition.gateway.redundancy.RedundancyManagerImpl$ExecuteTask.run(RedundancyManagerImpl.java:760)
 	at com.inductiveautomation.ignition.common.execution.impl.BasicExecutionEngine$ThrowableCatchingRunnable.run(BasicExecutionEngine.java:546)
 	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
 	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
 	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
 	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
 	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
 	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
 	at java.lang.Thread.run(Thread.java:748)

```

---

<div class="post-metadata">

**Author:** ![sjackson](https://avatars.discourse-cdn.com/v4/letter/s/f6c823/32.png) [@sjackson](https://forum.inductiveautomation.com/u/sjackson)\
**Post date:** [July 27, 2017, 2:24pm UTC](https://forum.inductiveautomation.com/t/unsatisfiedlinkerror-in-native-method-when-using-jni/14782/2 "2017-07-27T14:24:45Z")

</div>

I have found the solution to check to see if it is already loaded and if it is to not reload it with code from [This guy](https://github.com/JavaGtk/JavaGtk/blob/master/src/main/java/org/java_gtk/util/NativeLibrariesHelper.java)…