XF 1.4 Looking to block non utf-8 characters

The non utf-8 character ’ causes some problems for my forum, is there any way to either block this character or convert it to ' which is a utf-8 character? I don't want users to make any use of that certain character, or any non utf-8 for that matter
 
All input from users is validated as UTF-8. You appear to have used the character here without issue so what problem did you have?
 
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