httpx Instances of `tempfile.TemporaryFile` fail when used

The Fix

Upgrade to version 0.13.0 or later.

Based on closed encode/httpx issue #530 · PR/commit linked

Production note: Most teams hit this during upgrades or environment changes. Roll out with a canary and smoke critical endpoints (health, OpenAPI/docs) before 100%.

Jump to Verify Open PR/Commit

@@ -48,7 +48,7 @@ def __init__(
         self.name = name
         if not isinstance(value, tuple):
-            self.filename = Path(getattr(value, "name", "upload")).name
+            self.filename = Path(str(getattr(value, "name", "upload"))).name
             self.file = value  # type: typing.Union[typing.IO[str], typing.IO[bytes]]

repro.py

venv/lib/python3.7/site-packages/httpx/client.py:484: in post
    trust_env=trust_env,
venv/lib/python3.7/site-packages/httpx/client.py:616: in request
    cookies=cookies,
venv/lib/python3.7/site-packages/httpx/client.py:356: in build_request
    cookies=cookies,
venv/lib/python3.7/site-packages/httpx/models.py:696: in __init__
    content, content_type = self.encode_data(data, files, json)
venv/lib/python3.7/site-packages/httpx/models.py:619: in encode_data
    content, content_type = multipart_encode(data or {}, files)
venv/lib/python3.7/site-packages/httpx/multipart.py:100: in multipart_encode
    for field in iter_fields(data, files):
venv/lib/python3.7/site-packages/httpx/multipart.py:93: in iter_fields
    yield FileField(name=name, value=value)
venv/lib/python3.7/site-packages/httpx/multipart.py:51: in __init__
    self.filename = Path(getattr(value, "name", "upload")).name
/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/pathlib.py:994: in __new__
    self = cls._from_parts(args, init=False)
/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/pathlib.py:649: in _from_parts
    drv, root, parts = self._parse_args(args)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

cls = <class 'pathlib.PosixPath'>, args = (29,)

    @classmethod
    def _parse_args(cls, args):
        # This is useful when you don't want to create an instance, just
        # canonicalize some constructor arguments.
        parts = []
        for a in args:
            if isinstance(a, PurePath):
                parts += a._parts
            else:
              a = os.fspath(a)
E               TypeError: expected str, bytes or os.PathLike object, not int

verify

Re-run the minimal reproduction on your broken version, then apply the fix and re-run.

fix.md

Option A — Upgrade to fixed release\nUpgrade to version 0.13.0 or later.\nWhen NOT to use: This fix is not applicable if the file handling logic requires the original integer behavior.\n\n

Why This Fix Works in Production

Trigger: Instances of `tempfile.TemporaryFile` fail when used as an upload file.
Mechanism: Fixes the issue where instances of `tempfile.TemporaryFile` fail when used as an upload file by ensuring the filename is properly converted to a string.
Why the fix works: Fixes the issue where instances of `tempfile.TemporaryFile` fail when used as an upload file by ensuring the filename is properly converted to a string. (first fixed release: 0.13.0).

Production impact:

If left unfixed, the same config can fail only in production (env differences), causing startup failures or partial feature outages.

Why This Breaks in Prod

Shows up under Python 3.7 in real deployments (not just unit tests).
Production symptom (often without a traceback): Instances of `tempfile.TemporaryFile` fail when used as an upload file.

Proof / Evidence

GitHub issue: #530
Fix PR: https://github.com/encode/httpx/pull/545
First fixed release: 0.13.0
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.85
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.35

Discussion

High-signal excerpts from the issue thread (symptoms, repros, edge-cases).

Jump to Sources Open on GitHub

“When using tempfile.TemporaryFile the file.name attribute returns an integer, rather than the usual path string, which causes a breakage for us further down the line... Have also confirmed that the issue *doesn't* occur with tempfile.NamedT”

Issue thread · issue description · source

Failure Signature (Search String)

Instances of `tempfile.TemporaryFile` fail when used as an upload file.
E TypeError: expected str, bytes or os.PathLike object, not int

Copy-friendly signature

signature.txt

Failure Signature
-----------------
Instances of `tempfile.TemporaryFile` fail when used as an upload file.
E               TypeError: expected str, bytes or os.PathLike object, not int

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
Instances of `tempfile.TemporaryFile` fail when used as an upload file.
E               TypeError: expected str, bytes or os.PathLike object, not int

Minimal Reproduction

repro.py

venv/lib/python3.7/site-packages/httpx/client.py:484: in post
    trust_env=trust_env,
venv/lib/python3.7/site-packages/httpx/client.py:616: in request
    cookies=cookies,
venv/lib/python3.7/site-packages/httpx/client.py:356: in build_request
    cookies=cookies,
venv/lib/python3.7/site-packages/httpx/models.py:696: in __init__
    content, content_type = self.encode_data(data, files, json)
venv/lib/python3.7/site-packages/httpx/models.py:619: in encode_data
    content, content_type = multipart_encode(data or {}, files)
venv/lib/python3.7/site-packages/httpx/multipart.py:100: in multipart_encode
    for field in iter_fields(data, files):
venv/lib/python3.7/site-packages/httpx/multipart.py:93: in iter_fields
    yield FileField(name=name, value=value)
venv/lib/python3.7/site-packages/httpx/multipart.py:51: in __init__
    self.filename = Path(getattr(value, "name", "upload")).name
/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/pathlib.py:994: in __new__
    self = cls._from_parts(args, init=False)
/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/pathlib.py:649: in _from_parts
    drv, root, parts = self._parse_args(args)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

cls = <class 'pathlib.PosixPath'>, args = (29,)

    @classmethod
    def _parse_args(cls, args):
        # This is useful when you don't want to create an instance, just
        # canonicalize some constructor arguments.
        parts = []
        for a in args:
            if isinstance(a, PurePath):
                parts += a._parts
            else:
              a = os.fspath(a)
E               TypeError: expected str, bytes or os.PathLike object, not int

Environment

Python: 3.7

Fix Options (Details)

Option A — Upgrade to fixed release Safe default (recommended)

Upgrade to version 0.13.0 or later.

When NOT to use: This fix is not applicable if the file handling logic requires the original integer behavior.

Use when you can deploy the upstream fix. It is usually lower-risk than long-lived workarounds.

Fix reference: https://github.com/encode/httpx/pull/545

First fixed release: 0.13.0

Last verified: 2026-02-09. Validate in your environment.

When NOT to Use This Fix

This fix is not applicable if the file handling logic requires the original integer behavior.

Verify Fix

verify

Re-run the minimal reproduction on your broken version, then apply the fix and re-run.

Did This Fix Work in Your Case?

Quick signal helps us prioritize which fixes to verify and improve.

Prevention

Add a CI check that diffs key outputs after upgrades (OpenAPI schema snapshots, JSON payload shapes, CLI output).
Upgrade behind a canary and run integration tests against the canary before 100% rollout.

Version Compatibility Table

Version	Status
0.13.0	Fixed

Related Issues

No related fixes found.

Cluster: httpx:configuration-error All hubs All clusters

Related clusters: Data consistency Other Timeout

Sources

We don’t republish the full GitHub discussion text. Use the links above for context.

httpx Instances of `tempfile.TemporaryFile` fail when used as an upload file. (Fix)