I solved it with a tip I got : Mendix Userlib Cleaner.

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It could be that you have conflicting java libraries in you userlib folder of the application where it does happen, which could be caused by importing widgets. Next to that, it could be that this happens when you upgrade Mx versions or modules inside your project. I think that making an effort investigating this will be worthwhile. 
 

To solve these issues and/or prevent issues in the future it is always recommended to maintain the userlib folder clean, meaning with only the necessary files. Meaning, you have to remove basically any file that is not a jar library associated with the project. This can be done manually, by checking the modules used and the libraries associated with them vs what is in the userlib folder.

Another option is to use a tool developed by Cinaq, called Mendix Userlib Cleaner. To use it, follow these steps:

• Download the corresponding build from the release
• Unzip the mendix-userlib-cleaner.exe into your userlib you want to clean
  In Explorer window location write cmd and press enter. This opens a black terminal window
• In this terminal window write: .\mendix-userlib-cleaner.exe
• It should inform you what it will remove. Verify the output and to actually remove the jars write: .\mendix-userlib-cleaner.exe --clean

It is important to mention that this tool will ONLY check for libraries. If there is anything else in that folder that it is not a jar file or .Required extension then it should not be there and can be deleted. Please make sure to use this tool in a separate branch of your project and test carefully after using it, experience learns that in some occasions the tool removes to many libraries.

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Hi Chis, I did that but still getting errors, also in another app de javascript functions give the same error. :(

Uploaded the app to production, there the javascript actions work.