With Advanced Settings you control the format and capacity of the code, so if you specify too many characters or too high of an error correction level it will f

With Advanced Settings you control the format and capacity of the code, so if you specify too many characters or too high of an error correction level it will fail (with that rather unhelpful error). Try increasing the version (which adds more pixels in the X or Y direction), or adding a few slave blocks. (The above is based on my quick exploration with it on Safari, YMMV)