Hello, this Is just a bit annoying, but I remember that it didn't happen to me when I bought the RB4011 in May this year (v 6.48.3, soon will update to 6.48.4 but in the "What´s new" of 6.48.4 do not mention about it ). I´m no sure if this could be a problem from Winbox, or maybe from the router firmware.
When I´m inside Winbox configuration, and push the button Manual in the vertical left menu, the page https://wiki.mikrotik.com/wiki/Manual:TOC is open inside a new windows from Winbox.
The problem is that I always get this error attached in pictures, everytime a new page of the manual is opened, error is shown, but pasting the same link o any browser of my computer, it opens well, no errors, including Iexplorer 11, Chrome 92.0.4515.159 version, or firefox 89.0.2.
Thank you