# Getting java.lang.NoClassDefFoundError: io/gatling/core/cli/GatlingOptionParser when upgrading to 3.11.3
**URL:** https://community.gatling.io/t/getting-java-lang-noclassdeffounderror-io-gatling-core-cli-gatlingoptionparser-when-upgrading-to-3-11-3/9067
**Category:** Gatling (Open-Source)
**Tags:** release
**Created:** [June 10, 2024, 6:18am UTC](https://community.gatling.io/t/getting-java-lang-noclassdeffounderror-io-gatling-core-cli-gatlingoptionparser-when-upgrading-to-3-11-3/9067 "2024-06-10T06:18:02Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@nkatiyar](https://community.gatling.io/u/nkatiyar)
#### Post date: [June 10, 2024, 6:18am UTC](https://community.gatling.io/t/getting-java-lang-noclassdeffounderror-io-gatling-core-cli-gatlingoptionparser-when-upgrading-to-3-11-3/9067/1 "2024-06-10T06:18:02Z")
**Gatling version** : 3.11.2 (must be up to date)
**Gatling flavor** : [3.11.3] java [11] kotlin [karate-gatling=1.4.1] scala [2.13.14]
**Gatling build tool** : [maven] maven gradle sbt bundle
Adding exception here:
at java.base/java.lang.reflect.Method.invoke(Method.java:580)
at io.gatling.plugin.util.ForkMain.runMain(ForkMain.java:67)
at io.gatling.plugin.util.ForkMain.main(ForkMain.java:35)
Caused by: java.lang.NoClassDefFoundError: io/gatling/core/cli/GatlingOptionParser
at io.gatling.app.Gatling$.fromArgs(Gatling.scala:50)
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### Author:  [@nkatiyar](https://community.gatling.io/u/nkatiyar)
#### Post date: [June 10, 2024, 6:22am UTC](https://community.gatling.io/t/getting-java-lang-noclassdeffounderror-io-gatling-core-cli-gatlingoptionparser-when-upgrading-to-3-11-3/9067/2 "2024-06-10T06:22:52Z")
I am not referring to this class from my code. I am assuming it would be referred by one of the libraries I am using… I can see GatlingOptionParser class does not exist in latest version. Can you tell why and where is it still referred ?
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### Author:  [@slandelle](https://community.gatling.io/u/slandelle)
#### Post date: [June 10, 2024, 6:44am UTC](https://community.gatling.io/t/getting-java-lang-noclassdeffounderror-io-gatling-core-cli-gatlingoptionparser-when-upgrading-to-3-11-3/9067/3 "2024-06-10T06:44:43Z")
You’re most likely mixing Gatling libraries with different versions. You should be using `3.11.3` for all the Gatling libraries in your classpath.
Note: karate-gatling is not supported here. Please use genuine Gatling for load testing as the performance of this third party is really suboptimal.
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### Author:  [@slandelle](https://community.gatling.io/u/slandelle)
#### Post date: [June 10, 2024, 6:44am UTC](https://community.gatling.io/t/getting-java-lang-noclassdeffounderror-io-gatling-core-cli-gatlingoptionparser-when-upgrading-to-3-11-3/9067/4 "2024-06-10T06:44:50Z")