A Git Push Gets HTTP 417 Through the Proxy
HTTP 417 means an expectation was not met. Locate the response issuer before changing credentials or increasing Git's buffer settings.
A small Git operation works, while another returns HTTP 417. That status is not shorthand for “proxy password rejected.”
HTTP defines 417 as an expectation failure. A request carrying an Expect field can encounter a server or intermediary unable to meet that expectation. The 100-continue exchange explains the decision before the upload body is sent.
Find out which component issued the response and what the request contained. A carefully redacted Git HTTP trace and the proxy's corresponding log entry are more useful than guessing from the size of the commit.
If the internal repository should use a direct route, correct that routing policy deliberately. If it must use the proxy, investigate the compatibility of that path. Removing every proxy setting may hide the symptom by selecting another route without explaining the failure.
Likewise, http.postBuffer is not a universal cure for proxy errors. Use the Git configuration reference to understand the option before changing it. The numeric HTTP status, the request stage, and the component returning it should guide the next step.