# Odd error after running a gatling-it:test using the SBT plugin **URL:** \ **Category:** Gatling (Open-Source)\ **Created:** [September 3, 2019, 2:23pm UTC](https://community.gatling.io/t/odd-error-after-running-a-gatling-it-test-using-the-sbt-plugin/5220 "2019-09-03T14:23:05Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![jarrowwx](https://avatars.discourse-cdn.com/v4/letter/j/4af34b/32.png) [@jarrowwx](https://community.gatling.io/u/jarrowwx)\ **Post date:** [September 3, 2019, 2:23pm UTC](https://community.gatling.io/t/odd-error-after-running-a-gatling-it-test-using-the-sbt-plugin/5220/1 "2019-09-03T14:23:05Z")
I’m seeing an error at the end of the test run, and I’m wondering what it means. > sbt gatling-it:test com.example.testApp.ProveItWorks > … // test runs [info] Simulation ProveItWorks successful. [info] Simulation(s) execution ended. [success] Total time: 25 s, completed Sep 3, 2019, 10:11:42 AM [error] Expected ID character [error] Not a valid command: com [error] Expected project ID [error] Expected configuration [error] Expected ‘:’ [error] Expected key [error] Not a valid key: com (similar: compile, commands, scalaHome) [error] com.example.testApp.ProveItWorks [error] ^ Am I using it wrong? I couldn’t find anything on the current docs page for the plugin for how to run a particular simulation, so I’m just guessing on the syntax. SBT version 1.2.8 Gatling SBT Plugin 3.0.0 Gatling 3.2.0 ---
**Author:** ![slandelle](https://dub1.discourse-cdn.com/flex013/user_avatar/community.gatling.io/slandelle/32/4_2.png) [@slandelle](https://community.gatling.io/u/slandelle)\ **Post date:** [September 3, 2019, 2:29pm UTC](https://community.gatling.io/t/odd-error-after-running-a-gatling-it-test-using-the-sbt-plugin/5220/2 "2019-09-03T14:29:42Z")
You’re confusing gatling:test and gatling:testOnly. ---
**Author:** ![jarrowwx](https://avatars.discourse-cdn.com/v4/letter/j/4af34b/32.png) [@jarrowwx](https://community.gatling.io/u/jarrowwx)\ **Post date:** [September 3, 2019, 2:49pm UTC](https://community.gatling.io/t/odd-error-after-running-a-gatling-it-test-using-the-sbt-plugin/5220/3 "2019-09-03T14:49:52Z")
Found the answer. gatling-it:test runs everything, and does not expect a parameter. To run one, I needed to change :test to :testOnly. After making that change, it works fine. This is what happens when one takes a 4-year break from using Gatling… 😉 ---
**Author:** ![jarrowwx](https://avatars.discourse-cdn.com/v4/letter/j/4af34b/32.png) [@jarrowwx](https://community.gatling.io/u/jarrowwx)\ **Post date:** [September 4, 2019, 9:03pm UTC](https://community.gatling.io/t/odd-error-after-running-a-gatling-it-test-using-the-sbt-plugin/5220/4 "2019-09-04T21:03:32Z")
So now, all of a sudden, what used to be working is not working: > sbt gatling-it:testOnly com.example.testApp.ProveItWorks > [info] Loading settings for project gatling-sbt-seed-build from plugins.sbt … > [info] Loading project definition from /Users/jarrowwx/src/oss/gatling-sbt-seed/project > error: error while loading String, class file ‘/modules/java.base/java/lang/String.class’ is broken > (class java.lang.NullPointerException/null) > [info] Loading settings for project gatling-sbt-seed from build.sbt … > [info] Set current project to gatling-sbt-seed (in build file:/Users/jarrowwx/src/oss/gatling-sbt-seed/) > [info] Updating … > [info] Done updating. > [warn] There may be incompatibilities among your library dependencies; run ‘evicted’ to see detailed eviction warnings. > 16:58:49.058 [INFO] i.g.c.c.GatlingConfiguration$ - Gatling will try to use ‘gatling.conf’ as custom config file. > 16:58:50.795 [INFO] a.e.s.Slf4jLogger - Slf4jLogger started > 16:58:53.483 [INFO] i.g.h.e.HttpEngine - Start warm up > 16:58:54.144 [INFO] i.g.h.e.HttpEngine - Warm up done > **Simulation com.example.testApp.MultipleFlows started…** Any idea why it is suddenly launching the wrong simulation? ---
**Author:** ![slandelle](https://dub1.discourse-cdn.com/flex013/user_avatar/community.gatling.io/slandelle/32/4_2.png) [@slandelle](https://community.gatling.io/u/slandelle)\ **Post date:** [September 4, 2019, 9:25pm UTC](https://community.gatling.io/t/odd-error-after-running-a-gatling-it-test-using-the-sbt-plugin/5220/5 "2019-09-04T21:25:50Z")
You’ve upgraded to Java 12 and that causes a bug with sbt 1.2 which is supposed to be fixed in sbt 1.3.0 that was released today. ---
**Author:** ![slandelle](https://dub1.discourse-cdn.com/flex013/user_avatar/community.gatling.io/slandelle/32/4_2.png) [@slandelle](https://community.gatling.io/u/slandelle)\ **Post date:** [September 4, 2019, 9:27pm UTC](https://community.gatling.io/t/odd-error-after-running-a-gatling-it-test-using-the-sbt-plugin/5220/6 "2019-09-04T21:27:14Z")
Pretty sure “all of a sudden” actually is “after I’ve upgraded to Java 12” 😛 ---
**Author:** ![jarrowwx](https://avatars.discourse-cdn.com/v4/letter/j/4af34b/32.png) [@jarrowwx](https://community.gatling.io/u/jarrowwx)\ **Post date:** [September 5, 2019, 10:52am UTC](https://community.gatling.io/t/odd-error-after-running-a-gatling-it-test-using-the-sbt-plugin/5220/7 "2019-09-05T10:52:22Z")
It looks like I may have found the problem, and it may be a bug in either SBT or the plugin. Launching from the command line fails: > sbt gatling-it:testOnly com.example.testApp.ProveItWorks Launching from the sbt shell works > sbt > … > gatling-it:testOnly com.example.testApp.ProveItWorks If it helps to debug the issue, my code is checked in here: [GitHub - JohnArrowwood/gatling-sbt-seed: Gatling starter project, with all my favorite helper classes](https://github.com/JohnArrowwood/gatling-sbt-seed) ---
**Author:** ![phiSgr](https://dub1.discourse-cdn.com/flex013/user_avatar/community.gatling.io/phisgr/32/1437_2.png) [@phiSgr](https://community.gatling.io/u/phiSgr)\ **Post date:** [September 6, 2019, 6:36am UTC](https://community.gatling.io/t/odd-error-after-running-a-gatling-it-test-using-the-sbt-plugin/5220/8 "2019-09-06T06:36:07Z")
In command line, you need quotes to group them so that sbt knows the class name is a param of the command. BTW the following issue that contains the answer comes second in the Google search “gatling sbt testonly”. [https://github.com/gatling/gatling/issues/3360#issuecomment-335105340](https://github.com/gatling/gatling/issues/3360#issuecomment-335105340) ---
**Author:** ![Mishal\_Alexander](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Mishal\_Alexander](https://community.gatling.io/u/Mishal_Alexander)\ **Post date:** [September 10, 2019, 5:12am UTC](https://community.gatling.io/t/odd-error-after-running-a-gatling-it-test-using-the-sbt-plugin/5220/9 "2019-09-10T05:12:40Z")
Gatling doesn’t get along well with JDK 12 and also with the JRE that comes with it. I had all sorts of random stopping of script runs and other shenanigans like this until I downgraded my JDK to version 8 and JRE to version 9. If nothing works, my recommendation to you is to give this method a try. ---
**Author:** ![slandelle](https://dub1.discourse-cdn.com/flex013/user_avatar/community.gatling.io/slandelle/32/4_2.png) [@slandelle](https://community.gatling.io/u/slandelle)\ **Post date:** [September 10, 2019, 6:53am UTC](https://community.gatling.io/t/odd-error-after-running-a-gatling-it-test-using-the-sbt-plugin/5220/10 "2019-09-10T06:53:37Z")
Gatling only officially supports LTS releases, hence JDK 8 and 11. ---
**Author:** ![Mishal\_Alexander](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Mishal\_Alexander](https://community.gatling.io/u/Mishal_Alexander)\ **Post date:** [September 10, 2019, 8:57am UTC](https://community.gatling.io/t/odd-error-after-running-a-gatling-it-test-using-the-sbt-plugin/5220/11 "2019-09-10T08:57:55Z")
I had faced many issues with Gatling regarding the JAVA (JDK & JRE) versions and after a lot of trial and error, I have settled on these versions - JDK 8 and JRE 9. So I would recommend these over JDK 11. ---
**Author:** ![slandelle](https://dub1.discourse-cdn.com/flex013/user_avatar/community.gatling.io/slandelle/32/4_2.png) [@slandelle](https://community.gatling.io/u/slandelle)\ **Post date:** [September 10, 2019, 11:49am UTC](https://community.gatling.io/t/odd-error-after-running-a-gatling-it-test-using-the-sbt-plugin/5220/12 "2019-09-10T11:49:43Z")
Nah. Using different JDK and JRE versions is nonsensical. And I suspect the issues you had with JDK11 were actually an IntelliJ bug that was worked around in Gatling 3.2.1: [https://github.com/gatling/gatling/issues/3787](https://github.com/gatling/gatling/issues/3787). ---
**Author:** ![Mishal\_Alexander](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Mishal\_Alexander](https://community.gatling.io/u/Mishal_Alexander)\ **Post date:** [September 10, 2019, 12:12pm UTC](https://community.gatling.io/t/odd-error-after-running-a-gatling-it-test-using-the-sbt-plugin/5220/13 "2019-09-10T12:12:51Z")
Probably that might be the case, but nevertheless - my setup (JDK 8 and JRE 9) works without an issue so far. I don’t wanna “disturb” it to test IntelliJ again with JDK & JRE11 [it takes a lot of time to re-configure!]. You know, if it works, it works!