When using the command line package manager to create an ezcontentobject package I get this error several times:

Error: (eZFileHandler::copy)
Unable to open source file  in read mode

By doing a debug backtrace I found out that this error appears when empty attributes with the image datatype are exported. The serialization function of the eZImage datatype does not take into account that the attribute could be empty and tries to copy an empty path.

(first fix http://ez.no/community/bugs/ezpm_call_to_undefined_function_export_with_patch )