I'm also using roundup only with postgreSQL backends in several
installations. We're using our own custom date attributes.
I guess I've never tried to *sort* by date attributes though.

Interesting is the error you get. Roundup should sort this in SQL not in
python. Can you try to come up with a piece of code in roundup API that
reproduces this? Would be very valuable as a regression test item.

Ralf