Fix: Remove Default Port From HTTP/2 :authority Header (#7249)

Problem

Certain HTTP/2 servers reject requests when the :authority header includes a default port value that is already implied by the protocol. Axios previously generated an authority string like:

:authority: example.com:443

Even when the URL did not explicitly specify a port. Some HTTP/2 implementations expect the header to omit default ports and therefore responded with connection errors or rejected the request because the authority value was considered invalid.

Solution

The logic in lib/adapters/http.js has been updated to:

• Detect when a request is using HTTPS on port 443 or HTTP on 80
• Automatically omit the port in :authority when it is the protocol default
• Preserve ports when they are explicitly defined or are non-standard (e.g., 8080, 8443)

After this change, Axios now generates:

:authority: example.com

unless a custom port was intentionally provided.

Testing

A regression test has been added to confirm this behavior and ensure long-term consistency.

Impact

This change improves Axios compatibility with strict HTTP/2 servers by aligning the authority header formatting with expected protocol behavior. The update is non-breaking, does not alter API usage, and includes test coverage to prevent future regressions.