The error actually indicates a missing lib/xmpcore-6.1.10.jar file. Please verify that. It should be 139 978 bytes long.
Update: That IS the reason. I'll have to repackage and re-release the Linux version. I'll be back
Update again: It's rather that there is an old version of the xmpcore library lurking around. Please delete lib/xmpcore-5.1.2.jar and report how it behaves now.
Package jalbum-19.1-1.x86_64 actually owns 2 versions:
erlangen:~ # ll /usr/lib/jalbum/lib/xmpcore*
-rw-r--r-- 1 root root 86317 Nov 8 2014 /usr/lib/jalbum/lib/xmpcore-5.1.2.jar
-rw-r--r-- 1 root root 139978 Aug 25 02:54 /usr/lib/jalbum/lib/xmpcore-6.1.10.jar
erlangen:~ #
No adverse effects observed so far.