[BUG] Katalon Studio 8.0.0 java.lang.ClassFormatError

Updated Katalon studio version from 7.4.0 to 8.0. I download the Katalon 8.0 from the github instead of updating directly from Katalon - Help - Check for Updates. Every time I run a script, I am getting this error: java.lang.ClassFormatError: Illegal method name “dataBasePackage.Sql.connectDB” in class CustomKeywords

I tried to delete Libs & bin folder from project location and open Katalon studio 8.0 again but it didn’t help. I am not able to trouble shoot the issue. Can any one help me here. Thanks in advance.

Hi @sshah,

This issue is a known issue from v7.9.0 when we upgrading Eclipse framework (including Groovy-Eclipse plugin), we planned to fix it in v8.0.5. For now, you can keep using KS from v7.4.0 to v7.8.2.


Hi @sshah @duyluong @Shin I am having same challenge in katalon studio V8.2.0


try removing <projectdir>/.cache folder.

In this folder stored the compiled class files of your custom keywords. The error indicates that a class file in the folder is in bad format: perhaps the file is there but has 0-bytes. I don’t know why.

By removing the .cache folder, you can let Katalon Studio to build the keyword class cleanly.

This topic was automatically closed 365 days after the last reply. New replies are no longer allowed.