How to fix error while loading shared libraries: libwx_gtk2u_html-2.8.so.0 while installing BOINC?

BOINC is available in the Ubuntu software repositories; unless you have a very specific, unusual need, you can just use this version. (Downloading and installing the version from the BOINC website can lead to dependency issues like the one you've encountered).

Simply run

sudo apt install boinc

and you will have a basic installation of the client and the manager.

Other boinc packages (for SETI@Home, Boinc Screensaver, etc) are available; you can see the list http://packages.ubuntu.com/search?keywords=boinc&searchon=names&suite=xenial&section=all