Can't launch appdesigner in R2019b on Win10

When I try to run appdesigner with no arguments, it fails:

>> appdesigner
Error using appdesservices.internal.browser.WebWindowController/startBrowser (line 103) 
Unable to start App Designer due to an internal error.

Unexpected exception in plug-in: 'Assertion violation'

Error in appdesservices.internal.browser.AbstractBrowserController/start (line 120)
            obj.startBrowser(obj.StartBrowserArguments);
Error in appdesservices.internal.peermodel.BrowserControllerFactory/launch (line 77)
            browserController.start();
Error in appdesigner.internal.application.AppDesignerWindowController/startBrowser (line 75)
                obj.BrowserController = browserControllerFactory.launch(initialBrowserState);
Error in appdesigner.internal.application.AppDesignEnvironment/startAppDesigner (line 103)
                obj.AppDesignerWindowController.startBrowser(obj.BrowserControllerFactory);
Error in appdesigner (line 28)
    appDesignEnvironment.startAppDesigner();

This is in R2019b on Windows 10.

I had just been running appdesigner previously. It had hung up and wouldn't respond, so I quit MATLAB and restarted it, and that's when I started getting the above error. I tried rebooting my machine and running appdesigner first thing after launching MATLAB, to no avail. I also tried clearing my path of anything not from MathWorks (i.e., anything not under C:\Program Files\MATLAB\R2019b), and still the same error.

Note: I have the GUIDE-to-AppDesigner converter add-on installed; I can't remove it because the "Add-Ons->Manage Add-Ons" doesn't do anything now. I did try removing the converter's directory from my path (it was the last thing in the path) before launching appdesigner, but I got the same error.

I saw some Ubuntu users in R2017 and R2018 were having a similar problem (see www.mathworks.com/matlabcentral/answers/397138). I couldn't do the library manipulation suggested there because it was for Linux, but I tried the other suggestion:

w = matlab.internal.webwindow('mathworks.com')

and MATLAB hung on this.

Any ideas? I really need to develop an app soon!

[Jalaj Gambhir]

Hi,

Please try the following steps and let me know the output/errors you might get:

>> cd(matlabroot)
>> ! bin/win64/MATLABWindow 

Proceed with the following steps if you are getting any error (Please attach the error as well)

>> webutils.htmlrenderer('chromium')
>> appdesigner

[David Mellinger]

>> ! bin/win64/MATLABWindow

It pops up a MATLAB window ["MATLAB for AI" or something like that] and shows this in the Command WIndow:

[0224/054113.332:INFO:native_window_win.cpp(142)]  CreateBrowser: Creating renderer process  
[0224/054113.363:INFO:client_handler.cpp(150)]  OnBeforeResourceLoad https://www.mathworks.com/ 
[0224/054114.477:INFO:client_handler.cpp(162)]  OnResourceResponse https://www.mathworks.com/ 
[0224/054114.477:INFO:client_handler.cpp(508)]  OnLoadStart  
[0224/054117.196:INFO:client_handler.cpp(532)]  OnLoadEnd  

...then it sits there until I interrupt it.

> webutils.htmlrenderer('chromium')
Your HTML rendering engine is now set to 'chromium'.
ans =
     1
> appdesigner
Error using appdesservices.internal.browser.WebWindowController/startBrowser (line 103)
Unable to start App Designer due to an internal error.

 Unexpected exception in plug-in: 'Assertion violation'
Error in appdesservices.internal.browser.AbstractBrowserController/start (line 120)
            obj.startBrowser(obj.StartBrowserArguments);
Error in appdesservices.internal.peermodel.BrowserControllerFactory/launch (line 77)
            browserController.start();
Error in appdesigner.internal.application.AppDesignerWindowController/startBrowser (line 75)
                obj.BrowserController = browserControllerFactory.launch(initialBrowserState);
Error in appdesigner.internal.application.AppDesignEnvironment/startAppDesigner (line 103)
                obj.AppDesignerWindowController.startBrowser(obj.BrowserControllerFactory);
Error in appdesigner (line 28)
    appDesignEnvironment.startAppDesigner(); 
80                  rethrow(e);
K>> 

Looks like the same error as before.

[David Mellinger]

BTW I did the cd(matlabroot)

command first, just didn't show it above

[Jalaj Gambhir]

Hi,

So the next suggested steps are:

1. Try removing the GUIDE to App Designer Migration Tool (although it is doubtful that it is causing the issue), you can remove it by locating it under 'C:\ProgramData\MATLAB\SupportPackages\R2019b\' and restarting MATLAB to see if the problem still persists.
2. If step 1 doesn't solve the problem, proceed with the following steps:

>> matlabroot
>> which matlab.internal.webwindow

3. The command below should return a new window with solid white content.

>> ww1 = matlab.internal.webwindow('about:blank');
>> ww1.show()

4. Now try connecting to an external website. Note that this command is slightly different from what you have already tried.

>> ww2 = matlab.internal.webwindow('https://mathworks.com');
>> ww2.show()

5. Finally, try connecting it to MATLAB, using the below commands, and let me know the ouptut/errors, so that we can further look into the issue.

>> ww3 = matlab.internal.webwindow(connector.getUrl(''));
>> ww3.show();

[Thomas Hermelin]

Hello,

It appears I have the same issue on r2021a.

Step 3 did not show anything. ww1 is created in the workspace. I am on windows 10

Do you have any suggestion ?

Thanks for your help

[Marcel Goldschen-Ohm]

I was also getting a similar error in R2021a and also could not open an internal webwindow. The problem went away when I removed from my path several packages that I had downloaded from GitHub, so you might try resetting your path to default and/or removing 3rd party add-ons you are not absolutely sure about and see if the problem persists or not. I have not attempted to dig into what about those packages was causing the problem, but the two I removed were https://github.com/oliver-carr/Time-Varying-Hidden-Markov-Model and HMM toolbox at https://www.cs.ubc.ca/~murphyk/Software/HMM/hmm.html. Hope it helps.

[Longfrei Bai]

I also have the same issue, even if I start with an empty path..