MATLAB 2023b Can not open apps made in MATLAB 2023b, and startup error

Hi there,

When matlab 2023b opens, it shows this in the console

And then when I tried to open a matlab app in the app designer, it would not open or run. Even if I made an app in the 2023b app designer, saved it, and tried to open it with the 2023 app designer again. I was getting this error:

and in the console

[Walter Roberson]

I would probably reinstall it all.

[Ryan]

I have already done that. Same issue

[Walter Roberson]

Move aside prefdir and start MATLAB again and see if the problem still happens.

[Ryan]

What do you mean "Move aside"

[Walter Roberson]

pd = prefdir();
newpd = pd + ".old";
movefile(pd, newpd);

[Ryan]

Okay i cleared out the folder, restarted matlab, and same error.

Answer 1

[Benjamin Kraus]

I would check for errors in your startup.m or pathdef.m.

Specifically, what is the output from:

which -all pathdef

Compare that to the output from these two commands:

userpath
matlabroot

• You should see at least one output from which -all pathdef, and that file should be located in your matlabroot.
• You may see another output from which -all pathdef, and that second copy might be located in your userpath. If you see a copy of pathdef.m located in your userpath, then there is a chance you have a pathdef.m that is either corrupted, or based on an old release of MATLAB (and incompatible with a new release of MATLAB). If you find a copy of pathdef.m inside your userpath, my recommendation would be to delete or rename that copy, so that MATLAB starts using the version that is part of the MATLAB installation.

If that doesn't work, then I would try this next:

which -all startup

• If you see any output from which -all startup, then check that file to see if it is doing anything that might be adding or removing things from the path.

If that doesn't work, you can try:

restoredefaultpath
rehash toolboxcache
savepath

See if that resolve the issue, but note that running savepath could create a new copy of pathdef.m that will work now, but won't work the next time you update MATLAB.

[Ryan]

This worked! I needed to set a new path for matlab.