KeyError: 'cost_usd' with Max subsription

[kzmszk]

I tried claude-code-sdk for python and the most basic sample didn't work properly.
I'm using claude code with Max subscription.
I think 'cost_usd' is used only with API_TOKEN users?

The env or errors are as follows:

$  uv pip list
Package           Version
----------------- -------
anyio             4.9.0
claude-code-sdk   0.0.10
idna              3.10
sniffio           1.3.1
typing-extensions 4.14.0
$ cat basic_sample.py
import anyio
from claude_code_sdk import query

async def main():
    async for message in query(prompt="What is 2 + 2?"):
        print(message)

anyio.run(main)

$ python basic_sample.py 
SystemMessage(subtype='init', data={'type': 'system', 'subtype': 'init', 'cwd': '/workspace/sdk', 'session_id': 'b2b8a840-a344-4761-8415-106d197d79db', 'tools': ['Task', 'Bash', 'Glob', 'Grep', 'LS', 'exit_plan_mode', 'Read', 'Edit', 'MultiEdit', 'Write', 'NotebookRead', 'NotebookEdit', 'WebFetch', 'TodoRead', 'TodoWrite', 'WebSearch'], 'mcp_servers': [], 'model': 'claude-sonnet-4-20250514', 'permissionMode': 'default', 'apiKeySource': 'none'})
AssistantMessage(content=[TextBlock(text='4')])
unhandled exception during asyncio.run() shutdown
task: <Task finished name='Task-4' coro=<<async_generator_athrow without __name__>()> exception=RuntimeError('Attempted to exit cancel scope in a different task than it was entered in')>
Traceback (most recent call last):
  File "/workspace/sdk/.venv/lib/python3.12/site-packages/claude_code_sdk/_internal/transport/subprocess_cli.py", line 193, in receive_messages
    yield data
GeneratorExit

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/workspace/sdk/.venv/lib/python3.12/site-packages/claude_code_sdk/_internal/transport/subprocess_cli.py", line 182, in receive_messages
    async with anyio.create_task_group() as tg:
               ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/workspace/sdk/.venv/lib/python3.12/site-packages/anyio/_backends/_asyncio.py", line 778, in __aexit__
    if self.cancel_scope.__exit__(type(exc), exc, exc.__traceback__):
       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/workspace/sdk/.venv/lib/python3.12/site-packages/anyio/_backends/_asyncio.py", line 457, in __exit__
    raise RuntimeError(
RuntimeError: Attempted to exit cancel scope in a different task than it was entered in
Traceback (most recent call last):
  File "/workspace/sdk/.venv/lib/python3.12/site-packages/claude_code_sdk/_internal/client.py", line 38, in process_query
    message = self._parse_message(data)
              ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/workspace/sdk/.venv/lib/python3.12/site-packages/claude_code_sdk/_internal/client.py", line 89, in _parse_message
    cost_usd=data["cost_usd"],
             ~~~~^^^^^^^^^^^^
KeyError: 'cost_usd'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/workspace/sdk/basic_sample.py", line 8, in <module>
    anyio.run(main)
  File "/workspace/sdk/.venv/lib/python3.12/site-packages/anyio/_core/_eventloop.py", line 74, in run
    return async_backend.run(func, args, {}, backend_options)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/workspace/sdk/.venv/lib/python3.12/site-packages/anyio/_backends/_asyncio.py", line 2310, in run
    return runner.run(wrapper())
           ^^^^^^^^^^^^^^^^^^^^^
  File "/home/node/.local/share/uv/python/cpython-3.12.11-linux-aarch64-gnu/lib/python3.12/asyncio/runners.py", line 118, in run
    return self._loop.run_until_complete(task)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/node/.local/share/uv/python/cpython-3.12.11-linux-aarch64-gnu/lib/python3.12/asyncio/base_events.py", line 691, in run_until_complete
    return future.result()
           ^^^^^^^^^^^^^^^
  File "/workspace/sdk/.venv/lib/python3.12/site-packages/anyio/_backends/_asyncio.py", line 2298, in wrapper
    return await func(*args)
           ^^^^^^^^^^^^^^^^^
  File "/workspace/sdk/basic_sample.py", line 5, in main
    async for message in query(prompt="What is 2 + 2?"):
  File "/workspace/sdk/.venv/lib/python3.12/site-packages/claude_code_sdk/__init__.py", line 101, in query
    async for message in client.process_query(prompt=prompt, options=options):
  File "/workspace/sdk/.venv/lib/python3.12/site-packages/claude_code_sdk/_internal/client.py", line 43, in process_query
    await transport.disconnect()
  File "/workspace/sdk/.venv/lib/python3.12/site-packages/claude_code_sdk/_internal/transport/subprocess_cli.py", line 152, in disconnect
    await self._process.wait()
  File "/workspace/sdk/.venv/lib/python3.12/site-packages/anyio/_backends/_asyncio.py", line 1082, in wait
    return await self._process.wait()
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/node/.local/share/uv/python/cpython-3.12.11-linux-aarch64-gnu/lib/python3.12/asyncio/subprocess.py", line 137, in wait
    return await self._transport._wait()
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/node/.local/share/uv/python/cpython-3.12.11-linux-aarch64-gnu/lib/python3.12/asyncio/base_subprocess.py", line 230, in _wait
    return await waiter
           ^^^^^^^^^^^^
asyncio.exceptions.CancelledError: Cancelled by cancel scope ffff923b21b0
$  

[r488it]

#3

[couloirextreme]

Having the same issue.

[oreoluwa-xyz]

I am as well.

[bam4564]

Also facing this issue

[ali-coplanet]

same here

[lunartown]

same here

[unclecode]

CLI’s JSON schema changed, it no longer returns cost_usd, but the SDK still hard-codes that key inside _parse_message so the lookup bombs out, the exception cancels the AnyIO scope, and you see the CancelledError. I can make a PR propbably, but now very busy with Crawl4ai, so here is a zero-touch option plus a runtime shim:

# hot-patch missing `cost_usd` key so _parse_message stops blowing up
from types import MethodType
from claude_code_sdk._internal.client import InternalClient as _IC

_orig = _IC._parse_message
def _shim(self, data):
    if data.get("type") == "result":
        # both old and new JSON formats now covered
        data.setdefault("cost_usd", data.get("cost", 0.0))
        data.setdefault("total_cost", data.get("total_cost_usd",
                                               data.get("total_cost", data["cost_usd"])))
    return _orig(self, data)

_IC._parse_message = MethodType(_shim, _IC)

# Now use it, as it supposed to be
import anyio
from claude_code_sdk import query

async def main():
    async for message in query(prompt="What is 2 + 2?"):
        print(message)

anyio.run(main)

[unclecode]

I've fixed this issue! Here's the PR: #14

The fix handles the missing cost_usd field for Max subscription users by making it optional and using .get() with a default value.

This should resolve the KeyError while maintaining backward compatibility.

[ltawfik]

This is fixed with the latest SDK release, please pip install --upgrade claude-code-sdk, thanks everyone