Miro,
Despite the name of my directory qpc_3, which I reused from my precious QP/C install, I am indeed using QP/C and QDK 4.0. I was using IAR Workbench 5.11B, then I tried opening the project file with both Workbench 4.11A and 4.30F and got the same error in both cases:
The Project file 'C:\qpc_3\examples\avr\qk\iar\qdpp-butterfly\qdpp.ewp' was created by a newer version of the product and can not be opened. Which versions of of IAR Workbench is this port compatible with? Thanks