In Sentry CLI 2.x, we have assumed that 404 errors when getting the chunk upload options are due to the server not supporting chunked uploads. However, given that this endpoint has existed for quite some time, and given that Sentry CLI 3.x will only support servers that have this endpoint, in the 3.x release, we should assume a 404 error necessarily indicates that the organization does not exist, as this is the only possible cause of a 404 when using any recent Sentry version.

See also #2820 (CLI-176).