RuntimeError: dictionary changed size during iteration in anti_detection payload_obfuscator when sending JSON payload

[y3yhm]

Hi, thanks for maintaining ai-cloudscraper.

I found a reproducible RuntimeError when using ai-cloudscraper 3.8.4 with POST requests that pass payload via json=....

Observed error:
RuntimeError: dictionary changed size during iteration

Traceback consistently points to:
cloudscraper/anti_detection.py
pre_request_processing -> payload_obfuscator.obfuscate_payload -> _obfuscate_dict -> _encode_values
with the failing line similar to:
for key, value in data.items()

Important observations:

1. The issue reproduces under multiple modes:
   • hybrid + turbo
   • hybrid (without turbo)
   • compatibility_mode=True
2. It is not tied to one specific business payload. It appears in both:
   • /web/message
   • /marketplace/explore/items
3. Request snapshots show that the outgoing payload dict is structurally stable before request dispatch.
4. The problem seems to happen inside the library while processing kwargs['json'] during payload obfuscation.

Workaround on application side:
Converting all json=payload calls to:

• data=json.dumps(payload)
• plus Content-Type: application/json
  appears to avoid the failing obfuscation path.

Suspected root cause:
The library may be iterating over a dict while mutating it internally during payload obfuscation.

Suggested fix:
Please review the payload obfuscation path for kwargs['json'], especially any code that iterates over dict items while mutating the same dict.
A safer approach may be:

• iterate over list(data.items())
• or deep-copy the dict before mutation

Thanks.