Error with DiffusionQC module (GradQC)

Operating system: win10/Ubuntu 20
Slicer version: 4.11

After I install DiffusionQC extension, there come out an error whenever I star Slicer. I notice that GradQC failed to install, but I don’t know why.

Traceback (most recent call last):
File “”, line 1, in
File “C:\Users\Henry\AppData\Local\NA-MIC\Slicer 4.11.20210226\lib\Python\Lib\”, line 170, in load_source
module = _exec(spec, sys.modules[name])
File “”, line 618, in _exec
File “”, line 678, in exec_module
File “”, line 219, in _call_with_frames_removed
File “C:/Users/Henry/AppData/Local/NA-MIC/Slicer 4.11.20210226/NA-MIC/Extensions-29738/DiffusionQC/lib/Slicer-4.11/qt-scripted-modules/”, line 5, in
from gradqclib.slicerUserInteraction import slicerGUI
File “C:\Users\Henry\AppData\Local\NA-MIC\Slicer 4.11.20210226\NA-MIC\Extensions-29738\DiffusionQC\lib\Slicer-4.11\qt-scripted-modules\gradqclib\”, line 6, in
from diffusionqclib.dwi_attributes import dwi_attributes
File “C:\Users\Henry\AppData\Local\NA-MIC\Slicer 4.11.20210226\NA-MIC\Extensions-29738\DiffusionQC\Lib\site-packages\diffusionqclib\”, line 4, in
from nhdr_write import nhdr_write
ModuleNotFoundError: No module named ‘nhdr_write’

And the same problem happend in Ubuntu system.

I’m not sure if DiffusionQC extension developers monitor the Slicer forum, so it could be useful to report the problem at their issue tracker. Please copy here the link to the bug report.

Fail to instantiate module “GradQC” with Slicer 4.11 · Issue #46 · pnlbwh/SlicerDiffusionQC (

Relative import necessary for Slicer-4.11 · Issue #42 · pnlbwh/SlicerDiffusionQC (

There are some changes in version 4.11 and DiffusionQC don’t match the new version. I reinstalled version 4.10, but didn’t find the extension at all in Extensions Manager. Weird…

You cannot use extensions that are built for Slicer with a different major or minor version. Thanks for including links to the bug reports, I can see that you are working with the developer to resolve the issues.