I've used to say "except of" for a lot of sentences but recently someone noted (or corrected) me "apart from". I don't really remember the context that this correction was in. Anyway, after sometime I saw this article in Cambridge which is talking about the difference between "except for" to "apart from". That says that my habbit to say "except of" is a mistake?
As noted in the comments, 'except of' is wrong. This error may be caused by confusion with with the exception of, as in With the exception of Jim, everyone must report for work at 8am.
As with the example above, sometimes these confusions arise because different forms of a word use different prepositions, or one form has a preposition while the other doesn't (e.g. discuss the problem (no preposition), have a discussion about the problem).