[Eeglablist] Version 2026 bug? Unable to rereference to the average reference and add back online ref

Fri Jun 26 19:40:39 PDT 2026

The issue is that 

EEG = pop_reref( EEG, [], 'refloc', struct('labels',{'Cz'}, 'type',{'eeg'}, 'theta',177.4959, 'radius',0.029055, 'X',-9.167, 'Y',-0.4009, 'Z',100.244, 'sph_theta',-177.4959, 'sph_phi',84.77, 'sph_radius',100.6631, 'urchan',EEG.nbchan+1, 'ref',{''}, 'datachan',0) );

Is adding a second channel Cz. If you already have a channel Cz and it does not have coordinates, you should add them instead in the channel editor (or from the command line using pop_chanedit). This is detailed in that page.

https://urldefense.com/v3/__https://eeglab.org/tutorials/05_Preprocess/rereferencing.html__;!!Mih3wA!FzwrfBmBPxLmdJ_Fasn-abQBAUGHpBk41qiqMFzw20WDRK_0wJutkbz3EN7zqsBdDxfK53TfMmd0QWF1HppIzz_d$ 

Best wishes,

Arno

> On Jun 17, 2026, at 08:37, Miller, Carol Anne via eeglablist <eeglablist at sccn.ucsd.edu> wrote:
> 
> I have encountered a problem similar to what Kelsey and Andrew described (prior to their posts). I was wondering if there have been any updates, like is it really a bug and if so has it been fixed?  Using Windows, EEGLAB 2025, Matlab 2024a.
> Full disclosure: I have not yet tried Andrew's workaround but am hoping I won't have to!
> 
> Thanks,
> Carol
> 
> 
> Carol A. Miller, Ph.D.
> 
> Professor of Communication Sciences and Disorders and Linguistics
> 
> 404K Ford Building
> 
> 498 Allen Road
> 
> University Park, PA  16802
> 
> cam47 at psu.edu
> 
> Pronouns:  she/her
> 
> My work day may look different than your work day. Please do not feel any pressure to respond out of your normal working hours.
> 
> ________________________________
> From: eeglablist <eeglablist-bounces at sccn.ucsd.edu> on behalf of Andrew Corcoran via eeglablist <eeglablist at sccn.ucsd.edu>
> Sent: Tuesday, May 19, 2026 5:14 AM
> To: eeglablist at sccn.ucsd.edu <eeglablist at sccn.ucsd.edu>
> Subject: [Eeglablist] Version 2026 bug? Unable to rereference to the average reference and add back online ref
> 
> I recently experienced a similar problem to Kelsey when trying to adapt some old code for new BioSemi data using EEGLAB 2026 in MATLAB 2025a.
> 
> With some playing around via the gui I managed to get things working as follows :
> 
> % import chanlocs & define chantype
> EEG = pop_chanedit(EEG, {'lookup','standard_1005.elc'});
> 
> % assign ref
> EEG = pop_reref( EEG, [ contains({EEG.chanlocs.labels}, {'Cz'} ) ] );
> 
> % reintroduce Cz & reref to common average
> EEG = pop_chanedit(EEG, 'append', EEG.nbchan, 'changefield', {EEG.nbchan+1,'labels','Cz'}, ...
>        'lookup', 'standard_1005.elc');
> 
> EEG = pop_reref( EEG, [], 'refloc', struct('labels',{'Cz'}, 'type',{'eeg'}, ...
>        'theta',177.4959, 'radius',0.029055, 'X',-9.167, 'Y',-0.4009, 'Z',100.244, ...
>        'sph_theta',-177.4959, 'sph_phi',84.77, 'sph_radius',100.6631, 'urchan',EEG.nbchan+1, ...
>        'ref',{''}, 'datachan',0) );
> 
> While this code appears to function as intended, running it produces the following warning :
> Warning: some channels have the same label
> 
> I cannot see any evidence of incorrect labelling despite the warning. Whatever the source of the issue, it appears to be the same problem as previously raised on this list by Raquel London https://urldefense.com/v3/__https://nam10.safelinks.protection.outlook.com/?url=https*3A*2F*2Fsccn.ucsd.edu*2Fpipermail*2Feeglablist*2F2016*2F011065.html&data=05*7C02*7Ccam47*40psu.edu*7C925cf2493b44435f40b108deb59e7799*7C7cf48d453ddb4389a9c1c115526eb52e*7C0*7C0*7C639147889381256261*7CUnknown*7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ*3D*3D*7C0*7C*7C*7C&sdata=dULJSVZlLGdsKJAWuaDiKUo40ZGZ2qMYOBRT9rZugks*3D&reserved=0__;JSUlJSUlJSUlJSUlJSUlJSUlJSUlJSUl!!Mih3wA!BKijivb65F94Fh3pakg9Ea433tP9cJtHZ8YhJahPfm_O_VMmOZ2TiTTMrpByWciehp1wSuW1rY3ZBfQjSWE$ <https://sccn.ucsd.edu/pipermail/eeglablist/2016/011065.html   >  (I’m not sure if anyone got to the bottom of it).
> 
> Venlig hilsen
> Andrew
> 
> Dr. Andrew W. Corcoran
> Postdoctoral Researcher
> 
> Københavns Universitet
> Institut for Idræt og Ernæring<https://urldefense.com/v3/__https://nam10.safelinks.protection.outlook.com/?url=https*3A*2F*2Furldefense.com*2Fv3*2F__https*3A*2F*2Fnexs.ku.dk*2F__*3B!!Mih3wA!CpsvdSQpAQtDgps7UcdHM6iIBWQoB77bprwNjhp1wo1SFvi8cNP0jI6p3Iqrle4fkR5Y6wFkqPX4w0blhx8-4g*24&data=05*7C02*7Ccam47*40psu.edu*7C925cf2493b44435f40b108deb59e7799*7C7cf48d453ddb4389a9c1c115526eb52e*7C0*7C0*7C639147889381286684*7CUnknown*7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ*3D*3D*7C0*7C*7C*7C&sdata=j9UJTHx1YLw4rDJQAFYZkyjyUZJ*2F1bep7sh*2Batgve34*3D&reserved=0__;JSUlJSUlJSUlJSUlJSUlJSUlJSUlJSUlJSUlJSUl!!Mih3wA!BKijivb65F94Fh3pakg9Ea433tP9cJtHZ8YhJahPfm_O_VMmOZ2TiTTMrpByWciehp1wSuW1rY3ZGofja5A$  >
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