Our OpenStack vendor did some upgrades to their infrastructure, which broke upload to swift in a single place in our system.

Only trace in logs was:

RESP BODY: b'Unsupported Transfer-Coding header value specified in Transfer-Encoding header'

So if you are poor soul that has similar problem here is what I found.

For some reason our provider decided to throw away PUT with Transfer-Encoding: chunked header.

Swift uses following heuristic to determine whether to send Content-Length or Transfer-Encoding:

If swiftclient.service.SwiftService.upload gets an

• upload that has a read method client treats it as a file-like and proceeds to use Transfer-Encoding;
• if it gets a path it reads size, and then either sends Content-Length for small files or uses Transfer-Encoding for files bigger than maximal object size (usually 5GB).

In my case I was uploading an unpacked zip archive, so I just cached zip entries to a temporary file and uploaded that.