Craft 3: Upload user photo from front end
The field name used for the user photo has changed to photo, so the bare minimum change to make this work is modifying
&lt;input type="file" id="userPhoto" name="userPhoto" value="Upload"&gt;
to be
&lt;input type="file" id="userPhoto" name="photo" value="Upload"&gt;

You'll probably want to use transforms, when outputting that image, too.

Also, I'd stick with currentUser.photo or currentUser.getPhoto(), instead of using a hybrid currentPhoto.getPhoto, but that might just be me.