When the attribute flow-name of the fo-element fo:flow is missing, FOP produces a NullPointerException. After adding the attribute everything works fine.
I tried FOP-version 0.20.2 and 0.20.3rc and both are affected.
Fixed in CVS maintenance branch
*** Bug 8698 has been marked as a duplicate of this bug. ***
batch transition pre-FOP1.0 resolved+fixed bugs to closed+fixed