Message Service fatally disconnected

hi,

I am recently seeing the following error popup while running my code in MATLAB R2019b.

JavaScript Alert - https://localhost:31515

Message Service fatally disconnected.

it happens randomly and i would like to know what could be the cause of it and how to fix it.

I never had this issue while running R2014b and it suddenly started when I switched to R2019b. My computer is running under Windows 10 pro (build 1909).

thank you in advance.

yuki

[NGUYEN Nho Gia Hien]

Just adding more info to this question:

I'm on Ubuntu 18.04 with MATLAB 2020a and having the same issue. It seems this is not OS specific error.

[John Anderson]

hi, the same thing for me, I'm also using Ubuntu 18.04 with MATLAB 2020a. Any help will be greatly appreciated !

[YUKI GOYA]

I increased the java heap memory size to 1024MB recently and it seems to fix the issue for now, but I cannot tell for sure...

[Weijie Liu]

The same for me. macOS Catalina 10.15.6 with MATLAB R2019b

[Amin Salehi]

Same here, following, MacOS Big Sir

Answer 1

[Patrik Forssén]

Got this error also and (local) help-pages stoped working. Not even reinstallation of MATLAB (R2020a, Win 10) helped to resolve the issue.

Seems to be a problem with corrupt preferences. After deleting the preferences directory, and reinstallation, help worked again with no error messages (so far). Type

prefdir

in the MATLAB command window, exit MATLAB and delete the preferences directory (WARNING! all your custom settings will be lost). I do not think reinstallation is actually necessary after that, just re-starting MATLAB should be sufficent.

After you have set your custom preferences again you might want to exit MATLAB and save a backup copy of the preferences directory so you can replace it if you experience similar problems again.

[Maximilian Prilmueller]

I am currently affected by the same error message, however the broken part of the Program is the Editor.

Deleting the preferences did not work.

Running Matlab with administrator rights resolves the issue of not displayed editor, but is not an option for regular use. It is a quick fix, though and might be helpful to other users. Using R2022a currently.