Getting a Katalon Error - "Multiple Groovy compilers found on classpath."

Web Testing
1

Hello,

Can someone please help resolve the below “Multiple Groovy compilers found on classpath.” error that I am seeing while performing test execution in Katalon Studio?

Katalon Studio Compilers Error
Katalon Studio Compilers Error1916×1015 126 KB

2

Quick Fix (Try This First)

Step 1: Clean the Project

  1. Close Katalon Studio

  2. Navigate to your project folder

  3. Delete these folders/files:

    • bin/

    • Libs/

    • .cache

    • .classpath

    • .project

  4. Reopen the project in Katalon Studio — it will regenerate these files with the correct classpath

Step 2: Check for Conflicting Plugins

  1. Go to Katalon Studio > Preferences > Katalon > Plugins

  2. Look for any custom plugins you’ve installed

  3. Temporarily disable non-essential plugins

  4. Restart Katalon and test

If the error disappears, one of your plugins is bundling a conflicting Groovy version

Step 3: Check build.gradle for Groovy Dependencies

If you have a build.gradle file in your project:

  1. Open it and look for Groovy dependencies like:

    groovy

    dependencies {
    implementation 'org.codehaus.groovy:groovy:3.0.17' // or similar
    }

  2. Remove or comment out any explicit Groovy dependencies — Katalon bundles its own

  3. Save and rebuild the project

If You’re Using Custom Keywords/Plugins

If you developed custom keywords or installed plugins from Katalon Store:

  • Check the plugin’s build.gradle or pom.xml for Groovy dependencies

  • Ensure they use Katalon’s bundled Groovy (not a separate version)

Last Resort: Reinstall Katalon

If the above doesn’t work:

  1. Backup your projects

  2. Uninstall Katalon Studio

  3. Delete the config folder:

    • Windows: <Katalon_Install_Dir>\config\

    • Mac: ~/Library/Application Support/Katalon/

  4. Reinstall the latest Katalon Studio version

  5. Reopen your project

Most likely cause: A custom plugin or external JAR is bundling its own Groovy compiler, conflicting with Katalon’s bundled version. Start with Step 1 (clean project) — that resolves 80% of these cases.

3

As per the image posted, you are using the sample project in katalon, so I guess the project didn’t get import nicely.
It is sure that some files in build.gradle, Drivers folder or Plugins folder got downloaded twice or so.

Simply clean up the project and open again, if it works then it is okay, otherwise re-import the sample project.

4

If you cannot re-import the project as you might have created tests already then

Delete these folders/files:

  • bin/

  • Libs/

  • .cache

  • .classpath

  • .project

Reopen the project in Katalon Studio — it will regenerate these files with the correct classpath

Then inspect the below mentioned folder in the project

  1. build.gradle
  2. Drivers folder
  3. Plugins folder

Find out the duplicate Groovy libraries and remove then and then save it

5

I also got this issue sometime back. I followed below steps it helped me clear the error.

Right click on this

image
image1770×721 195 KB

Then click on the ‘Quick Fix’ option. And follow what it says in next dialog box.

That should solve your issue.

6

Quick and easy way

7

yeah that’s what we guys need when stuck with actual problems.

8

This is just pure theory. Will never work in actual.

9

Yes , you are right

10

Hmm totally agree with your point

11

@vyasdhaval19

In your project folder C:\Users\vyasd\Katalon Studio\Sample Web Testing Project there is a file named .classpath. Open it using your favorite text editor, and make a search with key groovy.

On my machine, I found a line that contains groovy-x.x.x.jar, like this:

	<classpathentry kind="lib" path="/Applications/Katalon Studio.app/Contents/Eclipse/configuration/resources/lib/groovy-3.0.17.jar"/>

I want you to check if you find multiple lines in the .classpath file with groovy-x.x.x.jar. ---- this is what the error message says “Multiple Groovy compiles found on classpath.” Please check.

If you find them, the absolute path of groovy-x.x.x.jar would suggest what to do next.