Some years ago, I have created a 3D mesh from an .nrrd file, using Volume Rendering using Slicer version 4.11 and saved it into a .mrml file. When I open this .mrml file in Slicer 5.2 the 3D volume does not show up and i get the following error in the Python console:
[Qt] class QList __cdecl qSlicerCoreIOManagerPrivate::writers(const class QString &,const class QMap<class QString,class QVariant> &,class vtkMRMLScene ) const warning: Unable to find node with ID “” in the given scene.
Slicer version: 5.2.2
Can you still open this MRML file in 4.11 correctly? I.e., is the NRRD file still in the right place, or maybe it has been renamed?
You can still open the NRRD directly by dragging and dropping it into the Slicer window (5.2.2)
The mrml file opens correctly in Slicer 4.11 and the 3D volume is viewed properly.
Please use the latest Slicer Stable Release (currently Slicer-5.4.0) and let us know if you still see any errors. If you do then we would need a scene that reproduces the issue, so you can either share your scene (upload somewhere and post the link here or in a private message) or try to recreate a problematic scene with some sample data set and share that.
If the volume loads correctly just volume rendering does not appear then you can load just the NRRD file and set up volume rendering for this volume.