Close request body Payload on exception#12985
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The HTTP client did not close the request-body Payload when the body write failed part-way through (e.g. the server resets the TCP connection mid-upload). For file-backed bodies (open(path, "rb"), pathlib.Path, or FormData with a file field), the underlying OS file descriptor was leaked until garbage collection, so repeated failed uploads to a peer that disconnects mid-upload accumulate descriptors and can exhaust RLIMIT_NOFILE, denying service to the client process. This mirrors the server-side fix (Response.write_eof try/finally close) on the symmetric client path. The body is closed in ClientSession._request's terminal except BaseException handler, alongside the existing close on the success path and the redirect-abort branches. Closing here (rather than in ClientRequest._write_bytes) preserves the retry_persistent_connection path, which continues the request loop and must keep the body intact for retry. Payload.close() is idempotent, so this is safe even where abort branches already close the body.
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Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## master #12985 +/- ##
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Coverage 98.96% 98.96%
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Files 131 131
Lines 48087 48127 +40
Branches 2496 2497 +1
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+ Hits 47587 47627 +40
Misses 376 376
Partials 124 124
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Jun 23, 2026
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