Describe the bug

When an open file handle is given with a PUT request it is internally converted to a BufferedReaderPayload. Before the request is sent, the file handle is read and advanced when preparing the data. If certain error types are hit a retry happens within _request after that point. A new BufferedReaderPayload is constructed from the same underlying file handle, which has now advanced beyond what has been sent. When the data is prepared this time, it is missing an earlier chunk of data.

Included is a script with a minimal test case.

To Reproduce

Run the attached script.

Expected behavior

Internal retries should reset file handlers back to their original position (whether that's 0, or the start of the previous chunk that failed to send).

Logs/tracebacks

n/a

Python Version

3.14.3

aiohttp Version

Name: aiohttp
Version: 3.14.3
Location: /home/bhearsum/tmp/2026-08-05/bad/.venv/lib/python3.14/site-packages
Requires: aiohappyeyeballs, aiosignal, attrs, frozenlist, multidict, propcache, yarl
Required-by:

multidict Version

$ python -m pip show multidict
Name: multidict
Version: 6.7.1
Location: /home/bhearsum/tmp/2026-08-05/bad/.venv/lib/python3.14/site-packages
Requires:
Required-by: aiohttp, yarl

propcache Version

Name: propcache
Version: 0.5.2
Location: /home/bhearsum/tmp/2026-08-05/bad/.venv/lib/python3.14/site-packages
Requires:
Required-by: aiohttp, yarl

yarl Version

$ python -m pip show yarlName: yarl
Version: 1.24.5
Location: /home/bhearsum/tmp/2026-08-05/bad/.venv/lib/python3.14/site-packages
Requires: idna, multidict, propcache
Required-by: aiohttp

OS

Linux

Related component

Client

Additional context

No response

Code of Conduct

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