Misdemeanor on BG check

Accepted a job at a large financial firm. Background check came back with a DISMISSED misdemeanor D from last year for weed. My last BG check this did not come up... i thought since I was never convicted. But it is showing up now... They originally only asked me of convictions and financial crimes which I have NONE... They are asking about it and im worried I will loose the job. I was never charged, therefor innocent. Can this be held against me. I already took a drug test for them too and passed.

Is it safe to tell them i was found not guilty by dismissal or are those 2 things different (dismissed, not guilty) ?

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