801
I hate API like this
(i.imgur.com)
- This is Microsoft.
- He returns Webhook success with a code 200 and plaintext 1.
- He returns Webhook failure with a code 200 and a string tells its endpoint returned error 400.
- the string didn't tell what exactly the error.
- Don’t be like Microsoft.
EDIT: Got a few details wrong since this happens a few months ago and this meme used to be on r/ProgrammerHumor. Also the proof: 
There's a video somewhere by someone... Returning a blank document instead of an error code is sometimes a QoS decision. Clients won't make a new request without the user intervention, so whatever resource that's bottlenecked has time to catch up