Tracking issue for a maintainer to pick up. Splits the legitimate fix out of #7243 so the actual bug from #6968 can land cleanly.

Background

axios.postForm / putForm / patchForm in lib/core/Axios.js currently force a placeholder header on the overlay config:

headers: isForm ? { 'Content-Type': 'multipart/form-data' } : {}

The intent is to let the adapter rewrite this with a real boundary later. That works on:

• The browser XHR adapter (the platform appends the boundary).
• The Node HTTP adapter via the form-data package (getHeaders() overwrites it).
• The fetch adapter / spec-compliant FormData via formDataToStream (boundary attached).

It does not work on React Native Android. RN is neither hasStandardBrowserEnv (axios deliberately excludes RN in resolveConfig) nor does it use form-data. The bare placeholder reaches the wire untouched, and Android's networking layer rejects multipart/form-data without a boundary. iOS is more permissive, which is why this only reproduces on Android.

Original report: #6968. Attempted fix: #7243 (closed — see review for why that diff isn't the right shape).

Proposed fix

In lib/core/Axios.js, in the post/put/patch helper factory, drop the placeholder entirely:

return this.request(mergeConfig(config || {}, {
  method,
  url,
  data
}));

(Or headers: {} if we'd rather be explicit.) config.headers is already merged in by mergeConfig(config || {}, …) — the second argument is the overlay, not the source — so anything the caller passes still flows through. No placeholder, nothing to overwrite, no Android breakage.

The toFormData.js changes in #7243 should not be carried over:

• Function('return this')() is eval in a different shape; trips CSP without unsafe-eval (most production browsers behind a CSP, several RN setups).
• The precedence flip from PlatformFormData || FormData to runtimeFD || PlatformFormData silently breaks Node: Node 18+ has global FormData, so this picks the spec-compliant one over form-data, and any caller of axios.toFormData(obj) on Node who relied on .getHeaders() / .getLength() gets an object without them.
• It isn't needed for the RN bug — RN bundlers resolve the browser field in package.json, so PlatformFormData already points at lib/platform/browser/classes/FormData.js, which resolves to the RN runtime's FormData.

Tests required

• postForm / putForm / patchForm no longer emit a bare Content-Type: multipart/form-data placeholder.
• Node form-data path still ends up with Content-Type: multipart/form-data; boundary=… via getHeaders().
• Spec-compliant FormData path through the http adapter still gets a boundary via formDataToStream.
• Caller-provided Content-Type on the request config is preserved through the FormData helpers.

Acceptance

• Fix lands in lib/core/Axios.js only.
• Regression tests in tests/unit/ covering the three paths above.
• patchForm, postForm, putForm always give out Network Error on Android, but it worked just fine on IOS #6968 closes when this ships.