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Data unit 'A.U.' is not supported by newest update of MNE #14520
Description
Description of the problem
When trying to load a CW fNIRS snirf file with the latest verions (1.13) I get this error message: RuntimeError: The data unit 'A.U.' is not supported by MNE. Please report this error as a GitHub issue to inform the developers. This was not an issue in 1.12. I traced the issue to _get_dataunit_scaling of mne.io.snirf._snirf.py, where 'A.U.':'arbitrary units' does not have a unit specified, so it throws the error. I suggest adding to line 695, where if no unit is given then a scaling of 1.0 is assigned. I suggest changing the line from if unit == "": -> if unit == "" or unit.lower() == 'a.u.': to catch this and similar cases.
Steps to reproduce
read_raw_snirf(snirf_file, preload=True)Link to data
No response
Expected results
load successfully
Actual results
throws error RuntimeError: The data unit 'A.U.' is not supported by MNE. Please report this error as a GitHub issue to inform the developers.
Additional information
In latest version 1.3.2. Not present in earlier version 1.12.1
Activity
scott-huberty commentedon Nov 11, 2026
This error is confusing, because MNE does generally support arbitary unit data, e.g. here:
mne-python/mne/defaults.py
Line 54 in a43fb22
mne-python/mne/defaults.py
Lines 68 to 69 in a43fb22
This sounds reasonable to me!
cc @jcrdubois , looks like they added the error message that you are reporting, in #1398
viranovskaya commentedon Nov 12, 2026
Hi! Have you already started working on this? If not, would it be okay if I took it on?
alfredcurry commentedon Nov 12, 2026
I have tested that line change I suggested in my own download, but haven't made a pull request to update the actual repo. You are welcome to do it