Inactivated - An exception to the rule?

I thought experienced is the only word which begins with a vowel and the antonym of which is formed by prefixing the word with ‘in’.
Recently, I came across the word “inactivated” somewhere and confirmed its existence.
Did I get it wrong about the rule?

Correction. I meant an adjective ending with “ed”.

I am not sure with the rule.
But I think the right word is deactivated, not inactivated.

Yeah, such a rule is there concerning antonyms of the adjectives ending in ‘ed’.
It’s a known fact that ‘inexperienced’ is the only word which is an exception to this rule.
Now, I doubt that after having known about the word ‘inactivated’
As regards the existence of the word, please check that out in a search engine.
It’s a synonym of deactivated.