What error code should we use when historical versions are missing?

[josephg]

This issue is a follow-up to #90 . The spec is now intentionally ambiguous about which error code to send when historical versions are missing or unavailable on the server.

I proposed 416 Range Not Available, but it was raised that 416 might not make sense given the request wasn't a range request.

Alternate suggestions:

• Add a new status code - but that might be difficult to get by HTTPBIS
• Use 425 Too Early ? 412 Precondition Failed?
• Have the server respond with the current version of the document instead

It would be great to get some use cases for requesting historical versions from the server in general, to figure out what the client should do in cases like this.

[mitar]

I think 410 Gone is almost perfect for this: https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/410

Or maybe simply 404?