Configuration problem with TomCat / Java - base64 error

Job ID: 32821116

Budget: €8 – €30 EUR

We have a new version of an TomCat/Java application. The vendor changed how they use base64 decoding and switched from "import xxx.base64.Base64;" to "import java.util.Base64;" and later "Base64.toBinary" to "Base64.getDecoder().decode". With this change the problems started, log says "Illegal base64 character d".
In their documentation, they ask to make sure that "ISO-8859-1" is used. We have no idea how to get things running and the vendor says they cannot reproduce the problem.

So if you already solved that problem somewhere or know where to add parameters to get things running, this is your project.