note jimbojones Hi<p> The [mod://Archive::Zip] module will not compress members if the uncompressed size is 0. However, the <c>jar</c> command seems to add an additional "external local header" to the data.<p> So, when <c>A::Z</c> writes out the data, since it thinks it's 0 bytes, it writes out uncompressed, but also writes ou the external header(?), giving you the "only DEFLATED entries can have EXT descriptor" error.<p> This link seems to show something similar in python that might have some insights:<p> [http://mail.python.org/pipermail/python-bugs-list/2007-June/038900.html]</P> I tested this with <c>A::Z</c> v1.20, and I think it's a bug with A::Z. I was poking around in <c>A::Z::Member::rewindData</c> to see what it does with 0 byte compressed data.<p> Also, running zip against the file gives:<p> <c> >zip bar.jar zip warning: extended local header not found for META-INF/ zip error: Zip file structure invalid (bar.jar) </c> Hope this helps, Jim<p> 632286 632286