You are likely having issues with precedence. If you check Operator Precedence and Associativity, you'll see || is a very high precedence operator and or is a very low one. In your case, note that || is higher precedence than = and or is lower - || really is the correct choice.

I don't know who told || is no longer acceptable - while I certainly agree or tends to be easier to read, both are still valid constructs. If you are going to change all || to or, you can maintain functionality by liberal use of parentheses.