If you are using a mobile platform one possible cause is apple converts apostrophe's to either a left or right single quote. Some desktop browsers might do it too. I think that is causing the forum to choke. Note in the image you provided there is a "Incorrect string value \x92". the \x92 converts to a single quote on some platforms but the forum doesn't handle them, it uses apostrophes. If you are using an Apple phone do the following.
Turn smart punctuation off in Settings tapping General. Then, tap Keyboards, and toggle Smart Punctuation to off.
Eric