session locks when connected to internet; after disconnect it eventually unlocks with MATLAB error: JavaScript Alert - https://localhost:31515 Message service fatally disconne

Starting a few weeks ago I cannot run MATLAB (R2021a on a mac laptop) when connected to the internet. The session gets very slow and locks up. When I disconnect from the network, it eventually unlocks, and later a window pops up with the error message

MATLAB error:

JavaScript Alert - https://localhost:31515

Message service fatally disconnected

Searching on this message led to a suggestion to delete the prefernces file, but this did not help.

Answer 1

[Brian Stephenson]

Later I followed the Workaround in Bug Reports 2508122 and that seems to have fixed the problem.

MATLAB crashes when opening the help browser or searching in it (2508122)

Modified: 10/26/2021

Description

MATLAB might crash during either of the following actions:

Opening the help browser

Using the search string feature in the help browser on a machine behind a proxy server

Workaround

Use the following steps to work around this issue:

Regenerate your MATLAB preferences using these instructions:

https://www.mathworks.com/matlabcentral/answers/99625-how-do-i-regenerate-my-matlab-preferences

Restart MATLAB.

Change the documentation location to "Installed locally":

Open the MATLAB preferences by selecting Home > Environment > Preferences in the MATLAB Toolstrip.

In the left panel, click Help, then select Installed locally under Documentation Location.

Restart MATLAB.

Affected Release(s) Affected Product(s) Fix Options

MATLAB Get R2021b

R2021a MATLAB Get R2021a Update 5