Dear Alfonso,

I tested different pipelines (playing with versions of matlab and conn) and I succeed to make 1st level connectivity and I had some errors. 
I hope it can help to improve the conn21 version.
thanks anyway for that nice toolbox
Isabelle

open matlab 20b and conn21a
import fmriprep (1 sub x 2 runs)
save
close conn21
open conn20 (1st error below)
run setup (2nd error below)
run denoising (no error)
analysis 1st level : (yes !!) : done : start : done
analysis 1st level : new analysis : ROI to ROI only : select only network seeds : done : start. 
close conn20 
open conn21a
it asks to make again the denoising step, but at least the display of the analyses step is present
denoising : OK
analyses 1st level : I have access to the display, I can look at the results of both analyses I have done in conn20, change their settings and re-do the analysis, but I can't set a new default analysis (3rd error)


1st error:
ERROR DESCRIPTION:
Reference to non-existent field 'variables'.
Error in conn_updatefolders (line 157)
if ~isempty(CONN_x.Analyses(ianalysis).variables)&&isstruct(CONN_x.Analyses(ianalysis).variables)&&~isfield(CONN_x.Analyses(ianalysis).variables,'fbands'), CONN_x.Analyses(ianalysis).variables.fbands=repmat({1},size(CONN_x.Analyses(ianalysis).variables.names)); end
Error in conn (line 884)
if pobj.holdsdata, conn_updatefolders; end
Error in conn (line 4686)
conn('load',filename,true);
Error in conn_menumanager (line 121)
feval(CONN_MM.MENU{n0}.callback{n1}{1},CONN_MM.MENU{n0}.callback{n1}{2:end});
CONN20.b
SPM12 + Anatomy ArtRepair DAiSS DEM FieldMap MEEGtools TFCE cat12 conn marsbar pTFCE wfupickatlas xjviewBN
Matlab v.2019a
project: CONN21.a
storage: 1494.9Gb available
spm @ /mnt/data/soft/spm12
conn @ /mnt/data/soft/conn20
Project /crnldata/neuropain/isabelle/testCONN/conn_testMB_01.mat loaded

2nd error :
Ready to run Setup pipeline
overwrite existing results (re-compute for all subjects/ROIs)
local processing (run on this computer)
CONN: RUNNING SETUP STEP
Step 1/7: Checking data completeness
spm @ /mnt/data/soft/spm12
conn @ /mnt/data/soft/conn20
Checking if data files have been edited or moved. Please wait...
Step 2/7: Segmentation
Step 3/7: Importing conditions/covariates
Step 4/7: Importing functional data
Step 5/7: Importing ROI data
Step 6/7: Checking ROI data consistency across subjects
Step 7/7: Updating Denoising variables
Saving file. Please wait...ERROR DESCRIPTION:
Reference to non-existent field 'variables'.
Error in conn_updatefolders (line 157)
if ~isempty(CONN_x.Analyses(ianalysis).variables)&&isstruct(CONN_x.Analyses(ianalysis).variables)&&~isfield(CONN_x.Analyses(ianalysis).variables,'fbands'), CONN_x.Analyses(ianalysis).variables.fbands=repmat({1},size(CONN_x.Analyses(ianalysis).variables.names)); end
Error in conn (line 928)
conn_updatefolders;
Error in conn (line 4714)
conn('save',filename);
Error in conn (line 5746)
conn gui_setup_save;
Error in conn_menumanager (line 121)
feval(CONN_MM.MENU{n0}.callback{n1}{1},CONN_MM.MENU{n0}.callback{n1}{2:end});
CONN20.b
SPM12 + Anatomy ArtRepair DAiSS DEM FieldMap MEEGtools TFCE cat12 conn marsbar pTFCE wfupickatlas xjviewBN
Matlab v.2019a
project: CONN21.a
storage: 1494.9Gb available
spm @ /mnt/data/soft/spm12
conn @ /mnt/data/soft/conn20

3rd error :
Subscripted assignment between dissimilar structures.
Error in conn_batch (line 1364)
CONN_x.Analyses(ianalysis)=struct(...
Error in conn (line 7124)
case 'default', conn_batch('Analysis.name',tnames,'Analysis.sources',{},'Analysis.type','all','Analysis.measure','correlation (bivariate)'); conn_process('analyses_seedsetup',tnames); conn('gui_analysesgo',1);
CONN21.a
SPM12 + Anatomy ArtRepair DAiSS DEM FieldMap MEEGtools TFCE cat12 conn marsbar pTFCE wfupickatlas xjviewBN
Matlab v.2020a
project: CONN21.a
storage: 1486.3Gb available
spm @ /mnt/data/soft/spm12
conn @ /mnt/data/soft/conn21