NoClassDefFoundError sun/io/ByteToCharConverter with InterBase JDBC driver

The sun.* and sunw.* packages are internal and should not be used for exactly this reason. Seems like someone at InterClient screwed up. I'd advise you to contact them with a bug report, so they'll know to fix this for future releases.

If you can't wait for a future release, and are willing to break some licences (which I don't recommend of course). You may be able to create your own sun.io.ByteToCharConverter by copying the code from here, and adding it to the bootstrap classpath with -Xbootclasspath, but that would be a last resort.

Use db2jcc4.jar which is latest version. If you changed your mind to use Java 8 you need to use this.

I have the similiar problem and this change help me to fix the error.