What was your biggest job epic fail?

Built a Windows 8 app. Intentionally made it better than my Win32 app with an eye toward that being the platform of the future. Needless to say, it did not work out. Win32 app is still going strong though.

I have a funny story from my Support days :) I've been working at a call center and it was my second week there, so I was still very nervous. My English was pretty good but I still struggled with pronunciation and it didn't mix well with a stutter from being too scared. At the beginning of every call I had to introduce myself: "Hi! Thank you for calling XXX Tech Support, my name is Sonia". And one of the customers just couldn't get it. I repeated myself numerous times but he didn't hear me correctly. My favorite versions from him were: a) Sushi, and b) Sausage. Maybe he was too hungry 😁 But I had to stick with Sausage in order to solve his issue.

Spent 3 months building internal tooling (per request) for the sales lead to come and say it wasn't needed anymore.

Drove for 8 hours for a project requirement gathering, received a call from client stating that they are doing the project internally.

Once I confused a team chat with a client chat. And the client saw something he wasn't supposed to see....