"准不会有错的" can be translated into English as "It's bound to be correct" or "There's no doubt it will be right".
Here are some more natural and context-appropriate alternatives:
1、 "It's definitely correct." （这肯定是对的。）
2、 "You can be sure it's right." （你可以确定这是对的。）
3、 "It won't go wrong." （这不会出错的。）
4、 "There's no mistake in it." （这里面没有错误。）
Choose the one that best fits the context and tone you're aiming for.