# Running Simulations from IDE **URL:** \ **Category:** Gatling (Open-Source)\ **Created:** [November 6, 2014, 10:47am UTC](https://community.gatling.io/t/running-simulations-from-ide/1650 "2014-11-06T10:47:17Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Neil](https://avatars.discourse-cdn.com/v4/letter/n/839c29/32.png) [@Neil](https://community.gatling.io/u/Neil)\ **Post date:** [November 6, 2014, 10:47am UTC](https://community.gatling.io/t/running-simulations-from-ide/1650/1 "2014-11-06T10:47:17Z")
I was following [this wiki](http://gatling.io/docs/2.0.2/extensions/maven_archetype.html?highlight=maven) to setup my Eclipse for running gatling simulation, however got the following exception when I ran Engine.scala as “Scala Application” ` Exception in thread “main” java.lang.NoClassDefFoundError: scala/collection/GenTraversableOnce$class at com.dongxiguo.fastring.Fastring.(Fastring.scala:25) at io.gatling.core.util.StringHelper$$anon$1.(StringHelper.scala:53) at io.gatling.core.util.StringHelper$.(StringHelper.scala:53) at io.gatling.core.util.StringHelper$.(StringHelper.scala) at io.gatling.core.config.GatlingConfiguration$.mapToGatlingConfig(GatlingConfiguration.scala:134) at io.gatling.core.config.GatlingConfiguration$.setUp(GatlingConfiguration.scala:128) at io.gatling.app.Gatling$.fromMap(Gatling.scala:54) at Engine$delayedInit$body.apply(Engine.scala:13) at scala.Function0$class.apply$mcV$sp(Function0.scala:40) at scala.runtime.AbstractFunction0.apply$mcV$sp(AbstractFunction0.scala:12) at scala.App$$anonfun$main$1.apply(App.scala:76) at scala.App$$anonfun$main$1.apply(App.scala:76) at scala.collection.immutable.List.foreach(List.scala:381) at scala.collection.generic.TraversableForwarder$class.foreach(TraversableForwarder.scala:35) at scala.App$class.main(App.scala:76) at Engine$.main(Engine.scala:4) at Engine.main(Engine.scala) Caused by: java.lang.ClassNotFoundException: scala.collection.GenTraversableOnce$class at java.net.URLClassLoader$1.run(URLClassLoader.java:366) at java.net.URLClassLoader$1.run(URLClassLoader.java:355) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:354) at java.lang.ClassLoader.loadClass(ClassLoader.java:425) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308) at java.lang.ClassLoader.loadClass(ClassLoader.java:358) … 17 more ` Am I missing something ? Note that my simulation scripts is in “src/test/scala”. It runs fine from command line when I use the following ` mvn -Dgatling.simulationClass=MySimulationSimulation gatling:execute ` Neil ---
**Author:** ![Pierre\_DAL-PRA](https://avatars.discourse-cdn.com/v4/letter/p/ecccb3/32.png) [@Pierre\_DAL-PRA](https://community.gatling.io/u/Pierre_DAL-PRA)\ **Post date:** [November 6, 2014, 10:52am UTC](https://community.gatling.io/t/running-simulations-from-ide/1650/2 "2014-11-06T10:52:33Z")
My first guess : Either you are using an old Scala IDE which allows only one Scala version which is not the one’s Gatlings is using (Scala 2.10), or you’re using a newer Scala IDE, which defaults to Scala 2.11, which is not the one’s Gatling is using (not until Gatling 2.1). Please check that your installation of Scala IDE is configured to use Scala 2.10. ---
**Author:** ![Neil](https://avatars.discourse-cdn.com/v4/letter/n/839c29/32.png) [@Neil](https://community.gatling.io/u/Neil)\ **Post date:** [November 7, 2014, 4:28am UTC](https://community.gatling.io/t/running-simulations-from-ide/1650/3 "2014-11-07T04:28:08Z")
Yes I do see the following error markers Description Resource Path Location Type akka-actor\_2.10-2.3.6.jar is cross-compiled with an incompatible version of Scala (2.10). In case of errorneous report, this check can be disabled in the compiler preference page. blitz-lt Unknown Scala Classpath Problem fastring\_2.10-0.2.4.jar is cross-compiled with an incompatible version of Scala (2.10). In case of errorneous report, this check can be disabled in the compiler preference page. blitz-lt Unknown Scala Classpath Problem scalalogging-slf4j\_2.10-1.1.0.jar is cross-compiled with an incompatible version of Scala (2.10). In case of errorneous report, this check can be disabled in the compiler preference page. blitz-lt Unknown Scala Classpath Problem jsonpath\_2.10-0.6.1.jar is cross-compiled with an incompatible version of Scala (2.10). In case of errorneous report, this check can be disabled in the compiler preference page. blitz-lt Unknown Scala Classpath Problem redisclient\_2.10-2.13.jar is cross-compiled with an incompatible version of Scala (2.10). In case of errorneous report, this check can be disabled in the compiler preference page. blitz-lt Unknown Scala Classpath Problem scopt\_2.10-3.2.0.jar is cross-compiled with an incompatible version of Scala (2.10). In case of errorneous report, this check can be disabled in the compiler preference page. blitz-lt Unknown Scala Classpath Problem Not sure what is the fix. ---
**Author:** ![Neil](https://avatars.discourse-cdn.com/v4/letter/n/839c29/32.png) [@Neil](https://community.gatling.io/u/Neil)\ **Post date:** [November 7, 2014, 5:34am UTC](https://community.gatling.io/t/running-simulations-from-ide/1650/4 "2014-11-07T05:34:03Z")
I got it fixed. As Pierre said, I had to downgrade the scala version of the IDE. I removed the latest scala plugin from eclipse and installed the following [http://download.scala-ide.org/sdk/helium/e38/scala210/stable/site](http://download.scala-ide.org/sdk/helium/e38/scala210/stable/site) Thanks Neil