This issue comes when we upgrade from lower to higher version, Please check your userlib folder, and if you have several versions of log4j in there, remove the ones with the lowest version number, check other duplicate jar in your user lib folder and remove the duplicate. Once done press F4-(synchronize the app directory) and check the issue again.
Hi Vishva,
sounds like a typical userlib problem.
This can happen when you have multiple different versions of a library (e.g. Log4j) or you deleted a library by accident.
You can resolve the error by checking the userlib folder and remove the ones with the lowest version numbers. If you are missing the library try to reinstall the modules.
In newer versions Mendix introduced managed dependencies (Version 10.3.0+). It might help cleaning up the userlib folder and reinstall all modules to make use of the new managed dependency functionality.
Hope that helped
log4j-core-2.17.1.jar
log4j-api-2.18.0.jar
I Have this 2 jar files which one should delete and there is duplicate also only this files are there