mlapp won't open, urecognized method, property, or field DesignTimeProperties

Yes, I should back up more often and use different version numbers, so now I suffer a little.

I have been working on an app for a couple of years on a project, all of the recent work done in R2022b. Suddenly the mlapp won't open, and it won't let me access code to see what is wrong. I found this link from a staff member at The Mathworks (nice explanation, looks promising):

https://www.mathworks.com/matlabcentral/answers/653383-app-designer-matlab-2020b-does-not-open-mlapp-file

which is my current best guess. In January, I reduced the size of the axes, and I am guessing that I inadvertently modified the CreateFcn, clicked in the wrong place. Is there a way that I can get into the code to diagnose and fix the problem?

The error in R2023 beta, R2022b, 2020b, is that it is missing DesignTimeProperties.

In R2020a it says "Invalid input for argument 1 (rhs1): value must be a scalar.

I have a version from early January that I can open, but I would rather not have to remember what those recent changes were.

I would also like to know more generally how to get into an mlapp file's code if the app designer does not allow it, in case something like this happens again.

Answer 1

[Mario Malic]

Hi,

It's not recommended to mess with the app files as Benjamin wrote in the linked post. If you have a technical support available, they should be able to take care of it.

If you really need to sneak-peek into the file, just unzip/unpack it, make sure you back it up.

[Graeme]

Thank you, Mario. I did look at the app components (the sneak-peek), and I understand now what you are saying. It looks pretty easy for a user to mess things up working at that level. I did not find a reason for the corruption, but it must have been there.

I lucked out: my wife saved me. She was using a version of the app from early March that was still okay (family of nerds?), so I just needed to touch it up a bit. I don't know what I did wrong on the app, but from now on I will save version numbers every time I modify my apps.

I have a request to Mathworks: probably a really big request -- I found so many queries from people stuck in corrupted app files, unable to diagnose or fix the problem, that I think that it would be a huge benefit if there were a way to allow regular users to debug their corrupted apps. That would also help someone like me to learn what I did wrong to mess up the app.

Thank you again, Mario!