HTTP status codes / 4xx — Client error
408 Request Timeout
What it means
The client took too long to finish sending its request, so the server hung up.
What causes it
Slow or flaky client connection mid-upload; a client that opened a connection and stalled.
How to fix it
Retry on a stabler connection; for uploads, smaller chunks. Distinct from 504 — there a server-side upstream is the slow party.