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Error loading matlabprefs.mat

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Andreas Schwager
Andreas Schwager on 18 Jun 2021
Commented: Andreas Schwager on 25 Jun 2021
there is an error:
Unable to read MAT-file /home/myUser/.matlab/R2021a/matlabprefs.mat. Not a binary MAT-file. Try load -ASCII to read as text.
sometimes (this is not reproducible) it pops up after rebooting Matlab:
Warning: Initializing MATLAB Graphics failed.
This indicates a potentially serious problem in your MATLAB setup, which should be resolved as soon as possible. Error detected was:
Unable to read MAT-file /home/myUser/.matlab/R2021a/matlabprefs.mat. File might be corrupt.
> In hgrc (line 163)
In (line 15)
Some pages (e.g. recommend deleting matlabprefs.mat. However, if I do, the error pops up again.
I also deleted full ~/.matlab folder. The error was gone for a couple of hours. Now, it reappears.
Does anybody know a persistent solution?
Walter Roberson
Walter Roberson on 18 Jun 2021
That looks okay at the moment. At a time that MATLAB is telling you the file is corrupt, could you attach the file here for us to look at?
(Note: I am not completely sure where MATLAB stores github keys, or login credentials to reach your Mathworks account, and it is plausible they might be stored in that file, so there is some degree of security risk; I do not know if they are stored in that file or not, or how they might be encoded.)

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Accepted Answer

Jan on 19 Jun 2021
Edited: Jan on 25 Jun 2021
If removing the file helps for some time, a function is destroying the file. Then an approach is to scan, who is accessi ng the file. Shadow the builtin save() function by adding this in a folder ontop of the path:
function save(varargin)
file = varargin{1};
if contains(file, 'matlabprefs', 'IgnoreCase', true) % [EDITED, Typo fixed]
str =
evalin('caller', ['builtin(''save''', strjoin(varargin{:}, ',')]);
Does this work?! The strange calling syntax of the save() command, which takes char vectors as input to access the contents of the corresponding variables, is hard.
Andreas Schwager
Andreas Schwager on 25 Jun 2021
Dear Jan,
yes, I do not know when or why, however Matlab requires me to validate the local PCT cluster. This fails, if save is prevented. So, in the long term, there must be any better solution.

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