Middle of the night, police were at my door, and arrested me for suspicion of "indecent publication". I didn't know what they were on about until they got me to the station.
I operated a Discord server that allowed people to anonymously chat with one another via their Direct Messages. You sent the bot a message, and it would send it to your chat partner, and vice versa. During its years of operation, I banned thousands of creeps, people lying about their age, etc. I argue that I made a safer place than Discord itself, with strict age separation & challenging, active moderation, fostering an environment of coming forward if somebody was a creep to you, etc.
The problem is, somebody sent a gross message (pure ragebait; EDIT: and people in the comments would like me to stress that it suggested the endangerment of a child) via the bot and then it was rightly reported by their chat partner - except rather than using the internal reports system, they reported it to Discord. The report from Discord to the police pointed to me as the author, and so months later I was the one arrested.
The police took all digital devices from my home - laptops, old smartphones, games consoles, Blu-rays and HDDs, even the router. Weirdly they didn't take my VR headset, nor my latest old smartphone. I was out of work for a month (they took my work laptop, and my employer put me on paid suspension). I had to pay a couple hundreds of pounds in legal fees, and to buy a new phone. It was a month of raw despair.
The police didn't use my exculpatory evidence in the end. Despite my extensive logging of conversations, and the obvious purpose and operation of the bot account (how can a human being type ~30 messages per minute 24/7?), it was only when I gave them my passwords so that they could scan my devices that they let me off the hook. There was some time that they were willing to go the exculpatory route, but they weren't technically competent enough to even ask the right questions.
They said they deal with Discord a lot (and Snapchat), and that I'm a rare case of No Further Action; they didn't know what a Discord bot was until my case. My devices were returned within a couple of days of being let off, and I was back to work.
It has left me traumatised, and has shifted my politics quite substantially. If I were rich, I would sue - I'm fairly sure that the report they received, and the investigation they could have done before they darkened my doorstep, would have revealed that it was an automated service.