A jar file is corrupt or incomplete
What it looks like in your log
java.util.zip.ZipException: zip END header not found
What causes it
A jar failed to open: the download was cut short, the file was replaced while the server ran, or an HTML error page was saved where a jar should be.
How to fix it
Re-download the jar with the server stopped and check its size looks plausible. A jar of a few kilobytes is a web page in disguise.
Not sure this is your problem? Paste your log and Roastd will tell you which of these it actually matched, and what else it found.
Check your own log