by mistake

Accounts that were flagged by mistake could verify their age using a "video selfie" or by providing government-issued ID.

“Where is—” She almost said Simon by mistake.

But then she remembered how she had signed for the flowers and chocolates by mistake.

So is “Why, it seems I’ve taken your saddle by mistake, Miss Pevington; how could I be such a dunce?”

A total of 91 prisoners were freed by mistake between April and October this year, according to new government figures.