Why do I receive the error message "Error using load Unable to read file Permission denied"

I have a function which use Load and once in two I have this error message. I don't understand why. Can someone help me ?

[Adam Danz]

If you google "matlab Error using load Unable to read file Permission denied" there are lots of suggestions. Do you have a unique problem not addressed before?

[Gaëlle Sandront]

But none of the suggestion work and the program work sometimes

[Adam Danz]

Can you list the potential problems you've ruled out so far so we know where to start?

[Gaëlle Sandront]

I try to run matlab as an administrator, I did 'clear all' and they restart matlab but it also didn't work. I also try to change the permission. Maybe they other other possiblilities but i didn't find.

[Walter Roberson]

Are you using MS Windows? If you are then is it possible that the file you are trying to read is in use in another program?

[Adam Danz]

Is the file a mat file? If yes, does it load when you grad-and-drop it into the workspace? Perhaps the file is corrupt.

[Gaëlle Sandront]

What do you means by MS Windows ? I use windows 10 and I don't think so.

Yes it load.

[Adam Danz]

MS windows mean Microsoft Windows.

So it's a mat file and you can drag-n-drop but you can't us load().

Are you specifying the full file name inlcuding the path?

Can you show us the lines of code?

[Gaëlle Sandront]

I have in one function

Rii = psi_Rd(a);
Lii = psi_Ld(a);

filename = 'psidQ40.mat';
save(filename,'Rii', 'Lii')

and in an other one

load ('psidQ40.mat', 'Rii', 'Lii')

ant the 'a' is variable

[Adam Danz]

What happens when you specify the full path?

path = 'C:\Users\name\Documents\MATLAB';  %  <-- path to your mat file
filename = 'psidQ40.mat';                 %  <-- exact name of your mat file
load(fullfile(path, filename), 'Rii', 'Lii')

[Gaëlle Sandront]

It changes nothings, I still have the same problem.

[Adam Danz]

Could you attach the file?

[Walter Roberson]

Knowing the content of the file will not help for permission problems.

Permission problems can be due to security settings on the file, such as if the file was owned by a different user and you did not have authority to read the file. Those kinds of permission problems are a constant fact of life in a multiuser Unix setting, difficult to escape. They are also a factor in Window Server systems. In individual Windows systems, these kinds of permission problems are typically only noticed in the question of whether you have administrator rights to install or write new files underneath the Windows executable directories.

On MS Windows systems, permission problems can also show up if a file is already open when you try to use it. Unix distinguishes this situation from the "no permission" situation, returning an EBUSY or EAGAIN error instead of a EACCESS error.

Both Unix and MS Windows implement two kinds of locks: "advisory locks" and "mandatory locks". But (A) It is common on for MS Windows to make a mistake and enforce a mandatory lock in a situation that should be advisory; and (B) MS Windows applications that do not request shared access are automatically granted full mandatory exclusive access. Either way, it is common in MS Windows to end up in a situation in which one process opened a file, and no other process can read or write the same file until the first process closes the file. So if I ask to "read" a file in MS Windows, and I forget to say that other processes can have access to, then no other process can read or write the file until I remember to close the file or my process ends. By way of contrast: if I naively open a file for reading on Unix, and I do not remember to ask if anyone is writing to the file, then I can end up reading inconsistent content in the file. Both approaches have their advantages and disadvantages, but the MS Windows approach is a lot more likely to lock everyone out of a file that multiple processes are simply wanting to read.

[Adam Danz]

Yeah, but if we had the file we could rule out the possibility that it is corrupt as was this case in this situation:

https://www.mathworks.com/matlabcentral/answers/256978-why-do-i-get-error-using-load-can-t-read-file#answer_200880

[Walter Roberson]

Corrupt files do not say permissions denied though.

[Adam Danz]

ah... right.