Error: Unable to open file for writing. Check write permission.

I´m doing a code to generate a system composer report with sequence diagrams, but when i run the code, i get the error: Unable to open file 'C:\Users\user\OneDrive\Documents\MATLAB\image.png for writing. Check write permission. I checked that path and i do have writing permission, and i try running matlab as admin, but i get the same error. The tricky part is, if I run a simple code using the imwrite comand to save an image in that path (before running the report generator code i have), it works well and it writes an image there, but as soon as i run the repor generator code, i get the error, and if again, try to use the imwrite command (that previously worked) it throws the same error that said i don´t have write permission, but it had worked moments ago. Also, in the report generator code, in anypart of the code I specifed that i want to save the images in that specific path, matlab uses that path by default.

This is the report generator code:

import mlreportgen.report.*
import slreportgen.report.*
import slreportgen.finder.*
import mlreportgen.dom.*
import mlreportgen.utils.*
import systemcomposer.query.*
import systemcomposer.rptgen.finder.*

rpt = slreportgen.report.Report('OutputPath', 'FullArchitecture', ...
    'CompileModelBeforeReporting', false);
model = systemcomposer.loadModel(modelFileName);
if isempty(model)
    error('Model could not be loaded: %s', modelFileName);
end
seqDiagrams = model.getInteractions; 
if isempty(seqDiagrams)
    warning('No sequence diagrams found in the model: %s', modelFileName);
    return; % Exit if there are no diagrams
end
seqChapter = Chapter("Title", "Sequence Diagrams");
Sect = Section("Title", model.Name);
add(seqChapter, Sect);
try
    % Loop through each sequence diagram and add it to the report
    for i = 1:length(seqDiagrams)
        seqDiagram = seqDiagrams(i);
        % Create a SequenceDiagram reporter for each diagram
        seqReporter =     systemcomposer.rptgen.report.SequenceDiagram("Name", ...
            seqDiagram.Name, "ModelName", model.Name);
        seqSect = Section("Title", seqDiagram.Name);
        add(seqSect, seqReporter);
        add(Sect, seqSect);
    end
    % Add the chapter to the report
    add(rpt, seqChapter);  
catch ME
    fprintf('Error encountered: %s\n', ME.message);
end
% Finally, close and view or save the report (depending on platform)
close(rpt);

[dpb]

I don't see where the output file was defined in the code snippet attached.

Have you tried writing to a path on the local machine, not OneDrive just to make sure it isn't something with it? I hate that everything wants to default there any more; things end up places I never intended and can't find...

[Walter Roberson]

Writing directly to OneDrive is prone to sychronization errors. It is not rare to see write errors in tight loops but then to see the write errors disappear during debugging.

[Victoria Ramirez]

It doesn´t let me change where it saves the photos, because in anywhere in the code i especify the onedrive path, matlab just take that as a default and i don´t know how to change it. Any ideas on how can i do that?

Answer 1

[Vandit]

Hello Victoria,

Here are a few steps you can take to troubleshoot and potentially resolve the issue:

• Try changing the temporary directory used by MATLAB for storing images. You can set a different temporary directory by using "tempdir" functions to ensure it's writable. To know more about "tempdir" function, please refer to the below documentation: https://www.mathworks.com/help/matlab/ref/tempdir.html
• If MATLAB defaults to a specific path for saving images, try explicitly setting the path for the images in your report to a location you know is writable:

imageOutputPath = fullfile(tempDir, 'images');
mkdir(imageOutputPath);
% Ensure any image saving uses this path
setpref('Images', 'OutputPath', imageOutputPath);

Additionally, if you are using "save" function, please refer to the below MATLAB Answers thread which might resolve your query:

https://www.mathworks.com/matlabcentral/answers/330185-error-unable-to-open-file-image1-for-writing-you-might-not-have-write-permission

Hope this helps.

[Walter Roberson]

@Vandit

setpref('Images', 'OutputPath', imageOutputPath);

I do not recognize that ? Could you indicate where OutputPath of Images is documented?

OutputPath is a common property for report generator objects, but it is being set via

rpt = slreportgen.report.Report('OutputPath', 'FullArchitecture', ...
    'CompileModelBeforeReporting', false);

which does not appear to have anything to do with Images preferences?