After update Font Awesome Icons 5

there is already a thread for this,
check the link below

https://forums.osclasspoint.com/beta-osclass-theme/fontawesome-com-icons-some-not-display/

if its beta , use 4.7 that would be compatible.

Updated Awesome v5 and changed all icons only this.

where can find icon name ?

Which file ?

@osmad
Basically all theme files.

Not find the Icon name in theme files

@osmad
Some icons, like in checkbox, can be created via CSS as well (content).
You can right click on element to see stylesheet properties for it, you will need good css and html understanding to do such modificaitons.
Often, for font awesome 5, it is required just to change font name (font awesome 5 free .... or something like that) and font weight (normal or bold, depending on icon style).
You could also use "compatibility" font awesome sheet that should map v4 icons to v5, check their docs.