답변 있음 Message Service fatally disconnected
Got this error also and (local) help-pages stoped working. Not even reinstallation of MATLAB (R2020a, Win 10) helped to resolve ...
You can also select a web site from the following list:
How to Get Best Site Performance
Select the China site (in Chinese or English) for best site performance. Other MathWorks country sites are not optimized for visits from your location.