GUIDE Migration to App Designer: hObject, eventdata, handles <-> app, event

Hi,

I have several GUIDE apps that were developped on Matlab 2014/2018, and still run great even in 2024.

I have now upgraded to 2025/2026, and need to migrate to App Designer. I have used the GUIDE Migration strategies & provided plugin, and successfully converted the GUIDE .fig -> .m mlApp.

However, I am struggling to maintain backward compatibility with older Matlab version on the newly created .m files. I noticed that a lot of the code is now calling conversion functions such as

[hObject, eventdata, handles] = convertToGUIDECallbackArguments(app, event)

These do not exist on 2018b, is there a way to maintain 2018b compatibility on the newly migrated App Designer apps?

Undefined function 'convertToGUIDECallbackArguments' for input arguments of type 'xyz'.

Error in xyz/xyz_OpeningFcn (line 425)
            [hObject, eventdata, handles] = convertToGUIDECallbackArguments(app); %#ok<ASGLU>

Error in xyz (line 1043)
                runStartupFcn(app, @(app)xyz_OpeningFcn(app, varargin{:}))

Error in matlab.graphics.internal.figfile.FigFile/read>@(hObject,eventdata)xyz('figure1_ResizeFcn',hObject,eventdata,guidata(hObject))



Undefined function 'getRunningApp' for input arguments of type 'xyz'.

Error in xyz (line 461)
            runningApp = getRunningApp(app);



Undefined variable "appdesigner" or class "appdesigner.appmigration.UIControlPropertiesConverter".

Error in convertToGUIDECallbackArguments>localCreateHandles (line 115)
                    component = appdesigner.appmigration.UIControlPropertiesConverter(component);

Error in convertToGUIDECallbackArguments (line 43)
        handles = localCreateHandles(appFigure);

Error in xyz/STLSummaryWindow_OpeningFcn (line 425)
            [hObject, eventdata, handles] = convertToGUIDECallbackArguments(app); %#ok<ASGLU>

[Walter Roberson]

The documentation at https://www.mathworks.com/help/matlab/creating_guis/differences-between-app-designer-and-guide.html implies that the function still exists... and on my R2025b system I find it at /Applications/MATLAB_R2025b.app/toolbox/matlab/appdesigner/appdesigner/runtime/convertToGUIDECallbackArguments.m

[Rik]

If you need to maintain compatibility everywhere, you may also want to consider a complete rebuild of the graphical elements into a single pure m-file. That way you don't need to deal with .fig and .mlapp files that limit compatibility.

You could even choose to branch your code to use a figure on older releases and uifigure on newer releases.