I followed the hint and manually removed two images that overlapped a lot with other ones and it works now.
Still, in that case enblend could ignore an offending image completely (but throw a warning). Instead, no result image is written and the error message does not really help.
suggestion 1: include a more informative error message (offending image pairs, hint to remove one of the images)
suggestion 2: enblend could ignore all offending images (e.g. use the first one of a largely overlapping pair)
I followed the hint and manually removed two images that overlapped a lot with other ones and it works now.
Still, in that case enblend could ignore an offending image completely (but throw a warning). Instead, no result image is written and the error message does not really help.
suggestion 1: include a more informative error message (offending image pairs, hint to remove one of the images)
suggestion 2: enblend could ignore all offending images (e.g. use the first one of a largely overlapping pair)