Random Errors in Suite due to Illegal Method Name error

Please let us know what you are using Katalon Studio for?

  1. I have currently applied Katalon Studio in my project

How would your work be affected if this issue has not been resolved?

  1. I can continue my job, but my performance is lower than expected

Operating System

Windows 10

Katalon Studio Version


Katalon Studio logs

  • Windows logs folder: \config.metadata.log

  • macOS logs folder: file:///Applications/Katalon%20Studio.app/Contents/MacOS/config/.metadata/log

Screenshots / Videos

Environment (for Web testing):


Steps to reproduce:

Create a method.

Expected Behavior:

Method runs as expected.

Actual Behavior:

Test cases error out randomly through running a Test suite collection…

We have seen this as well when running Test Suite Collections via KRE on our TeamCity execution boxes. It seems there was a change earlier this month (Sept) where we started seeing this across our test execution machines that were running collections. There is also another error in particular where WebUI.navigateToUrl calls are also failing by timeout. It caused our test suite collection execution times to shoot throw the roof, then subsequently fail or hit execution timeouts. Can we please fix these issues with KRE soon? There are really quite problematic!

Hi Chase,

Glad to have you here with us,
If you not using Manual mode much you could try the solution on this Katalon 7.9 => error "Caused by: java.lang.ClassFormatError: CustomKeywords"
You can try deleting CustomKeywords.groovy from project lib folder for it to work.

If that happen again please let me know.

Hi Eric,

Could you state the bug in another topic with step to reproduce? This would really help.


Unfortunately, the New Topic button seems to be disabled for me at the moment…strange. Anyway, we’re currently in the process of acquiring full licensing for Katalon Studio and TestOps, as well as more runtime engine licenses, so we can have paid support and expand our capabilities. We have had so many weird issues since the beginning of September with running KRE via TeamCity, it would the length of a novel if I typed them all out here. It was working great up until that point, other than the usual Chrome Version/Chrome Driver Version mismatch issues. Trying to reproduce on your end would be impossible, as we orchestrate all kinds of stuff in TeamCity to make it happen…package the code from bitbucket, move it over to a VM, kickoff KRE on the VM, publish the reports to TeamCity, etc.

We’re currently pivoting to using the Katalon Docker image to run the tests, rather than maintaining VMs with updated versions of Katalon, Chrome, Web Driver, etc. I have a POC working on my local machine executing the tests in Docker. I just need to figure out how to get the reports to upload to TestOps, as we want to start using that for reporting and metrics. Then it should just be a matter of installing docker on a couple of machines, hooking those up as TeamCity agents, and building the execution profiles to kickoff the docker container, then call KRE inside the container.


What would the file path be to find the CustomKeyword.groovy file? I did a search and cannot find it. Also the solution posted about using imports instead is not a viable option for us as we have way too many tests that would need to be altered in order for that to happen. This error wasn’t an issue up until recently. Can we escalate this as it is severely hampering our regressions. Thanks!

Hi @Chase_Emerick,

The random error of Illegal method name when using Custom Keywords was addressed and fixed in v8.2.0. For now, you can try the beta version here.

Hi @eric.martin1,
You can download v8.2.0.beta also to experiment the fix of Custom Keywords error.

There is also another error in particular where WebUI.navigateToUrl calls are also failing by timeout.
For the second issue, please share with us the execution log

Morning Duyluong,

This is still occurring as of Katalon 8.2.0. Can we get this expedited as soon as possible… Thanks.

We are still getting the same error in latest version of Katalon -java.lang.ClassFormatError: Illegal method name “XXXXXXXXXXXXXXXXXXXXX” in class CustomKeywords
Do we have any suggestion how we can correct the same