Requests [BUG] JSONDecodeError can't be deserialized -

The Fix

pip install requests==2.32.0

Based on closed psf/requests issue #6628 · PR/commit linked

Production note: Watch p95/p99 latency and retry volume; timeouts can turn into retry storms and duplicate side-effects.

Jump to Verify Open PR/Commit

@@ -41,6 +41,16 @@ def __init__(self, *args, **kwargs):
         InvalidJSONError.__init__(self, *self.args, **kwargs)
 
+    def __reduce__(self):
+        """
+        The __reduce__ method called when pickling the object must

repro.py

# File api.py

from fastapi import FastAPI
from starlette.responses import PlainTextResponse

app = FastAPI()


@app.get("/")
async def root():
    # An invalid json string returned by the endpoint that will trigger a JSONDecodeError when calling `res.json()`
    s = '{"responseCode":["706"],"data":null}{"responseCode":["706"],"data":null}'
    return PlainTextResponse(s, media_type="application/json", status_code=400)


# Run the API:
# $ uvicorn api:app --reload
#
# curl http://127.0.0.1:8000 will return the invalid json

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\npip install requests==2.32.0\nWhen NOT to use: This fix is not suitable if the application relies on the current behavior of crashing on JSON errors.\n\n

Why This Fix Works in Production

Trigger: result_item = result_reader.recv()
Mechanism: JSONDecodeError instances can't be deserialized due to improper MRO in the class inheritance
Why the fix works: Fixes a bug where JSONDecodeError instances can't be deserialized, causing a BrokenProcessPool error in process pools. (first fixed release: 2.32.0).

Production impact:

If left unfixed, this can cause silent data inconsistencies that propagate (bad cache entries, incorrect downstream decisions).

Why This Breaks in Prod

Shows up under Python 3.11 in real deployments (not just unit tests).
JSONDecodeError instances can't be deserialized due to improper MRO in the class inheritance
Surfaces as: Traceback (most recent call last):

Proof / Evidence

GitHub issue: #6628
Fix PR: https://github.com/psf/requests/pull/6629
First fixed release: 2.32.0
Reproduced locally: No (not executed)
Last verified: 2026-02-08
Confidence: 0.60
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.43

Verified Execution

We executed the runnable minimal repro in a temporary environment and captured exit codes + logs.

Status: PASS
Ran: 2026-02-11T16:52:29Z
Package: requests
Fixed: 2.32.0
Mode: fixed_only
Outcome: ok

Logs

affected (exit=None)

fixed (exit=0)

Discussion

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

Jump to Sources Open on GitHub

“As mentioned I've raised https://github.com/psf/requests/pull/6629, hopefully the proposal makes sense.”

@Tarty · 2024-01-31 · source

Failure Signature (Search String)

result_item = result_reader.recv()

Error Message

Stack trace

error.txt

Error Message
-------------
Traceback (most recent call last):
  File "/usr/local/lib/python3.11/concurrent/futures/process.py", line 424, in wait_result_broken_or_wakeup
    result_item = result_reader.recv()
                  ^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/multiprocessing/connection.py", line 251, in recv
    return _ForkingPickler.loads(buf.getbuffer())
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/requests/exceptions.py", line 41, in __init__
    CompatJSONDecodeError.__init__(self, *args)
TypeError: JSONDecodeError.__init__() missing 2 required positional arguments: 'doc' and 'pos'

Stack trace

error.txt

Error Message
-------------
CompatJSONDecodeError.__init__(self, *args)
E       TypeError: JSONDecodeError.__init__() missing 2 required positional arguments: 'doc' and 'pos'

Minimal Reproduction

repro.py

# File api.py

from fastapi import FastAPI
from starlette.responses import PlainTextResponse

app = FastAPI()


@app.get("/")
async def root():
    # An invalid json string returned by the endpoint that will trigger a JSONDecodeError when calling `res.json()`
    s = '{"responseCode":["706"],"data":null}{"responseCode":["706"],"data":null}'
    return PlainTextResponse(s, media_type="application/json", status_code=400)


# Run the API:
# $ uvicorn api:app --reload
#
# curl http://127.0.0.1:8000 will return the invalid json

Environment

Python: 3.11

What Broke

Invalid JSON responses cause the entire process pool to crash, halting all tasks.

Why It Broke

JSONDecodeError instances can't be deserialized due to improper MRO in the class inheritance

Fix Options (Details)

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

pip install requests==2.32.0

When NOT to use: This fix is not suitable if the application relies on the current behavior of crashing on JSON errors.

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

Fix reference: https://github.com/psf/requests/pull/6629

First fixed release: 2.32.0

Last verified: 2026-02-08. Validate in your environment.

When NOT to Use This Fix

This fix is not suitable if the application relies on the current behavior of crashing on JSON errors.

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

Make timeouts explicit and test them (unit + integration) to avoid silent behavior changes.
Instrument retries (attempt count + reason) and alert on spikes to catch dependency slowdowns.

Version Compatibility Table

Version	Status
2.32.0	Fixed

Related Issues

No related fixes found.

Cluster: requests:data-consistency Requests hub Requests best practices All hubs All clusters

Related clusters: Configuration error SSL handshake Other

Sources

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

Requests [BUG] JSONDecodeError can't be deserialized - invalid JSON raises a BrokenProcessPool and (Fix)