Hello, I'm fiddling arround with some External Python Methods and I have to admit that it is a real pain to debug those Methods - at least I did not found a reasonable way. It makes me really crazy ist the fact that it seems that Zope just caches the first version of the file which I putted into the Extensions directory and later changes are simply ignored. For instance I just try to do some processing onto an image named bland.gif which is in the same folder of ZMI as the External Method. I've got a. Error Type: IOError Error Value: [Errno 2] No such file or directory: 'bland.gif' Well, besides the fact that I would like to know how to reference those files I really want to know why the following code stolen from http://www.zopelabs.com/cookbook/1010702887 works def MakeThumbHi2(self, image="test"): oriImage = self.restrictedTraverse(image) oriFile = cStringIO.StringIO(oriImage.data) image = PIL.Image.open(oriFile) image.thumbnail(100, 100) image_type = image.format thumbnailImage = cStringIO.StringIO() image.save(thumbnailImage, image_type) thumbnailImage.seek(0) return thumbnailImage.getvalue() and if I just replace my very own External Method by just this code snipped (please note: there is no string 'bland.gif' in it - it was just in my former broken code) I get the very same error message with the missing file 'bland.gif'. It seems that there is something cached and I would like to know how to get the changed version into this cache. Moreover it would be nice to enlighten me about some other way to reference files in the same ZMI folder from External Methods besides this way to ship a parameter. Kind regards Andreas.