Question regarding multichannel names

[unrpi18]

the dataset.json is:

"channel_names": {
"0": "CT",
"1": "CT"
},

Why is the above error reported for my image names xxxx.001.0000.nii.gz and xxxx.001.0001.nill.gz while I using the command nnUNetv2_plan_and_preprocess -d 001 -pl nnUNetPlannerResEncL ?

I'm currently using a macOS M3 chip, but I'm getting the same error with windows.

[TaWald]

Your dataset format seems off. you should separate with an underscore "_" and not a dot "."