Issue with AnyIO 4.15.0 – AttributeError: module 'anyio' has no attribute 'abc'

[ganiket19]

After upgrading anyio to version 4.15.0, the application started failing with the following error:

AttributeError: module 'anyio' has no attribute 'abc'

The issue appears to be related to an incompatibility with one of the dependencies that uses anyio.abc. The issue was not observed with the previous AnyIO version.

The current environment includes packages such as elastic-search,open-ai, which has an AnyIO dependency.

[ganiket19]

This are dependencies

"azure-ai-formrecognizer",
"azure-ai-ml",
"azure-ai-vision-imageanalysis",
"azure-cosmos>=4.5.1",
"azure-identity",
"azure-keyvault-secrets",
"azure-mgmt-storage",
"azure-mgmt-cosmosdb",
"azure-mgmt-datafactory",
"azure-mgmt-msi",
"azure-storage-blob",
"azure-storage-file-datalake",
"databricks-cli",
"databricks-connect~=15.4",
"databricks-sql-connector",
"elasticsearch>=8.10.0,<9.0.0",
"elastic-apm",
"jinja2",
"numpy",
"openai",
"pandas",
"pymsteams",
"pyyaml",
"retry",
"sendgrid",
"snowflake-connector-python>=4.0.0,<5"

[EmmanuelNiyonshuti]

Can you share a bit more about where this is failing in your application?

A full traceback and, if possible, a minimal reproducer (a small piece of code that is triggering the error) would help.

[ganiket19]

File /local_disk0/.ephemeral_nfs/cluster_libraries/python/lib/python3.12/site-packages/datalab_framework/utils/logging_setup.py:16
13 from logging import LogRecord
14 from pathlib import Path
---> 16 from elastic_transport import RequestsHttpNode
17 from elasticsearch import Elasticsearch
19 from datalab_framework.settings import settings
File /local_disk0/.ephemeral_nfs/cluster_libraries/python/lib/python3.12/site-packages/elastic_transport/init.py:22
18 """Transport classes and utilities shared among Python Elastic client libraries"""
20 import logging
---> 22 from ._async_transport import AsyncTransport as AsyncTransport
23 from ._exceptions import (
24 ApiError,
25 ConnectionError,
(...)
32 TransportWarning,
33 )
34 from ._models import ApiResponseMeta, HttpHeaders, NodeConfig, SniffOptions
File /local_disk0/.ephemeral_nfs/cluster_libraries/python/lib/python3.12/site-packages/elastic_transport/_async_transport.py:41
34 from ._exceptions import (
35 ConnectionError,
36 ConnectionTimeout,
37 SniffingError,
38 TransportError,
39 )
40 from ._models import DEFAULT, DefaultType, HttpHeaders, NodeConfig, SniffOptions
---> 41 from ._node import AiohttpHttpNode, BaseAsyncNode
42 from ._node_pool import NodePool, NodeSelector
43 from ._otel import OpenTelemetrySpan
File /local_disk0/.ephemeral_nfs/cluster_libraries/python/lib/python3.12/site-packages/elastic_transport/_node/init.py:21
19 from ._base_async import BaseAsyncNode
20 from ._http_aiohttp import AiohttpHttpNode
---> 21 from ._http_httpx import HttpxAsyncHttpNode
22 from ._http_requests import RequestsHttpNode
23 from ._http_urllib3 import Urllib3HttpNode
File /local_disk0/.ephemeral_nfs/cluster_libraries/python/lib/python3.12/site-packages/elastic_transport/_node/_http_httpx.py:39
36 from ._base_async import BaseAsyncNode
38 try:
---> 39 import httpx
41 _HTTPX_AVAILABLE = True
42 _HTTPX_META_VERSION = client_meta_version(httpx.version)
File /databricks/python/lib/python3.12/site-packages/httpx/init.py:2
1 from .version import description, title, version
----> 2 from ._api import delete, get, head, options, patch, post, put, request, stream
3 from ._auth import Auth, BasicAuth, DigestAuth, NetRCAuth
4 from ._client import USE_CLIENT_DEFAULT, AsyncClient, Client
File /databricks/python/lib/python3.12/site-packages/httpx/_api.py:6
3 import typing
4 from contextlib import contextmanager
----> 6 from ._client import Client
7 from ._config import DEFAULT_TIMEOUT_CONFIG
8 from ._models import Response
File /databricks/python/lib/python3.12/site-packages/httpx/_client.py:32
30 from ._transports.asgi import ASGITransport
31 from ._transports.base import AsyncBaseTransport, BaseTransport
---> 32 from ._transports.default import AsyncHTTPTransport, HTTPTransport
33 from ._transports.wsgi import WSGITransport
34 from ._types import (
35 AsyncByteStream,
36 AuthTypes,
(...)
50 VerifyTypes,
51 )
File /databricks/python/lib/python3.12/site-packages/httpx/_transports/default.py:32
29 import typing
30 from types import TracebackType
---> 32 import httpcore
34 from .._config import DEFAULT_LIMITS, Limits, Proxy, create_ssl_context
35 from .._exceptions import (
36 ConnectError,
37 ConnectTimeout,
(...)
49 WriteTimeout,
50 )
File /databricks/python/lib/python3.12/site-packages/httpcore/init.py:51
49 # The 'httpcore.AnyIOBackend' class is conditional on 'anyio' being installed.
50 try:
---> 51 from ._backends.anyio import AnyIOBackend
52 except ImportError: # pragma: nocover
54 class AnyIOBackend: # type: ignore
File /databricks/python/lib/python3.12/site-packages/httpcore/_backends/anyio.py:19
15 from .._utils import is_socket_readable
16 from .base import SOCKET_OPTION, AsyncNetworkBackend, AsyncNetworkStream
---> 19 class AnyIOStream(AsyncNetworkStream):
20 def init(self, stream: anyio.abc.ByteStream) -> None:
21 self._stream = stream
File /databricks/python/lib/python3.12/site-packages/httpcore/_backends/anyio.py:20, in AnyIOStream()
19 class AnyIOStream(AsyncNetworkStream):
---> 20 def init(self, stream: anyio.abc.ByteStream) -> None:
21 self._stream = stream
23 async def read(
24 self, max_bytes: int, timeout: typing.Optional[float] = None
25 ) -> bytes:
File /local_disk0/.ephemeral_nfs/cluster_libraries/python/lib/python3.12/site-packages/anyio/_lazyimport.py:41, in install_lazy_importer..getattr(name)
39 target_mod, target_attr = lazy_map[name]
40 except KeyError:
---> 41 raise AttributeError(
42 f"module {module_name!r} has no attribute {name!r}"
43 ) from None
45 imported = import_module(target_mod, module_name)
46 value = getattr(imported, target_attr)

[EmmanuelNiyonshuti]

It seems related to encode/httpcore#1106 ?

[EmmanuelNiyonshuti]

It seems related to encode/httpcore#1106 ?

Ah, I don't think this is related. I took a quick look and it's more likely because httpcore is doing something like this:

import anyio

anyio.abc.ByteStream

https://github.com/encode/httpcore/blob/10a658221deb38a4c5b16db55ab554b0bf731707/httpcore/_backends/anyio.py#L22

This is what seems to be triggering the AttributeError. anyio.abc is a submodule, and bare attribute access like this used to work in anyio<=4.14 because anyio eagerly imported everything at package-import time, #1169 changed that, I haven't deeply dug into this but I think whether anyio.abc resolves now depends on what else got imported first elsewhere in the process.

I am not very sure if this should be treated as a regression on anyio's end, or if it's more that downstream code should start importing submodules explicitly?

[EmmanuelNiyonshuti]

encode/httpcore#1107

[ksmdnl]

I also had the same bug when calling the service

/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
Registry store URI not provided. Using backend store URI.
2026/09/03 09:24:57 INFO mlflow.store.db.utils: Creating initial MLflow database tables...
2026/09/03 09:24:57 INFO mlflow.store.db.utils: Updating database tables
2026/09/03 09:24:58 INFO:     Uvicorn running on http://0.0.0.0:5006 (Press CTRL+C to quit)
2026/09/03 09:24:58 INFO:     Started parent process [41]
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
/usr/local/lib/python3.10/site-packages/mlflow/server/fastapi_app.py:19: StarletteDeprecationWarning: starlette.middleware.wsgi is deprecated and will be removed in a future release. Please refer to https://github.com/abersheeran/a2wsgi as a replacement.
  from starlette.middleware.wsgi import WSGIResponder, build_environ
/usr/local/lib/python3.10/site-packages/mlflow/server/fastapi_app.py:19: StarletteDeprecationWarning: starlette.middleware.wsgi is deprecated and will be removed in a future release. Please refer to https://github.com/abersheeran/a2wsgi as a replacement.
  from starlette.middleware.wsgi import WSGIResponder, build_environ
2026/09/03 09:25:01 INFO:     Started server process [47]
2026/09/03 09:25:01 INFO:     Waiting for application startup.
2026/09/03 09:25:01 INFO:     Application startup complete.
/usr/local/lib/python3.10/site-packages/mlflow/server/fastapi_app.py:19: StarletteDeprecationWarning: starlette.middleware.wsgi is deprecated and will be removed in a future release. Please refer to https://github.com/abersheeran/a2wsgi as a replacement.
  from starlette.middleware.wsgi import WSGIResponder, build_environ
/usr/local/lib/python3.10/site-packages/mlflow/server/fastapi_app.py:19: StarletteDeprecationWarning: starlette.middleware.wsgi is deprecated and will be removed in a future release. Please refer to https://github.com/abersheeran/a2wsgi as a replacement.
  from starlette.middleware.wsgi import WSGIResponder, build_environ
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
2026/09/03 09:25:01 INFO:     Started server process [45]
2026/09/03 09:25:01 INFO:     Waiting for application startup.
2026/09/03 09:25:01 INFO:     Application startup complete.
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
2026/09/03 09:25:02 INFO:     Started server process [44]
2026/09/03 09:25:02 INFO:     Waiting for application startup.
2026/09/03 09:25:02 INFO:     Application startup complete.
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
2026/09/03 09:25:02 INFO:     Started server process [46]
2026/09/03 09:25:02 INFO:     Waiting for application startup.
2026/09/03 09:25:02 INFO:     Application startup complete.
2026/09/03 09:25:04 INFO mlflow.server.jobs.utils: Registered online_scoring_scheduler periodic task (runs every 1 minute)
2026/09/03 09:25:04 INFO mlflow.server.jobs.utils: Registered trace_archival_scheduler periodic task (polls every 1 minute and no-ops when trace archival is disabled or unconfigured)
root@do-ki-team-worker:/home/jenkins/workspace# docker exec -it 1-gen-ai-backend sh
sh-5.2# curl http://1-mlflow:5006
Internal Server Errorsh-5.2# curl http://1-mlflow_server:5006
Invalid Host header - possible DNS rebinding attack detectedsh-5.2# ^C
sh-5.2# exit
exit
root@do-ki-team-worker:/home/jenkins/workspace# docker logs 1-mlflow_server
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
Registry store URI not provided. Using backend store URI.
2026/09/03 09:24:57 INFO mlflow.store.db.utils: Creating initial MLflow database tables...
2026/09/03 09:24:57 INFO mlflow.store.db.utils: Updating database tables
2026/09/03 09:24:58 INFO:     Uvicorn running on http://0.0.0.0:5006 (Press CTRL+C to quit)
2026/09/03 09:24:58 INFO:     Started parent process [41]
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
/usr/local/lib/python3.10/site-packages/mlflow/server/fastapi_app.py:19: StarletteDeprecationWarning: starlette.middleware.wsgi is deprecated and will be removed in a future release. Please refer to https://github.com/abersheeran/a2wsgi as a replacement.
  from starlette.middleware.wsgi import WSGIResponder, build_environ
/usr/local/lib/python3.10/site-packages/mlflow/server/fastapi_app.py:19: StarletteDeprecationWarning: starlette.middleware.wsgi is deprecated and will be removed in a future release. Please refer to https://github.com/abersheeran/a2wsgi as a replacement.
  from starlette.middleware.wsgi import WSGIResponder, build_environ
2026/09/03 09:25:01 INFO:     Started server process [47]
2026/09/03 09:25:01 INFO:     Waiting for application startup.
2026/09/03 09:25:01 INFO:     Application startup complete.
/usr/local/lib/python3.10/site-packages/mlflow/server/fastapi_app.py:19: StarletteDeprecationWarning: starlette.middleware.wsgi is deprecated and will be removed in a future release. Please refer to https://github.com/abersheeran/a2wsgi as a replacement.
  from starlette.middleware.wsgi import WSGIResponder, build_environ
/usr/local/lib/python3.10/site-packages/mlflow/server/fastapi_app.py:19: StarletteDeprecationWarning: starlette.middleware.wsgi is deprecated and will be removed in a future release. Please refer to https://github.com/abersheeran/a2wsgi as a replacement.
  from starlette.middleware.wsgi import WSGIResponder, build_environ
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
2026/09/03 09:25:01 INFO:     Started server process [45]
2026/09/03 09:25:01 INFO:     Waiting for application startup.
2026/09/03 09:25:01 INFO:     Application startup complete.
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
2026/09/03 09:25:02 INFO:     Started server process [44]
2026/09/03 09:25:02 INFO:     Waiting for application startup.
2026/09/03 09:25:02 INFO:     Application startup complete.
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
/usr/local/lib/python3.10/site-packages/requests/__init__.py:113: RequestsDependencyWarning: urllib3 (2.7.0) or chardet (7.6.0)/charset_normalizer (3.5.1) doesn't match a supported version!
  warnings.warn(
2026/09/03 09:25:02 INFO:     Started server process [46]
2026/09/03 09:25:02 INFO:     Waiting for application startup.
2026/09/03 09:25:02 INFO:     Application startup complete.
2026/09/03 09:25:04 INFO mlflow.server.jobs.utils: Registered online_scoring_scheduler periodic task (runs every 1 minute)
2026/09/03 09:25:04 INFO mlflow.server.jobs.utils: Registered trace_archival_scheduler periodic task (polls every 1 minute and no-ops when trace archival is disabled or unconfigured)
2026/09/03 09:28:16 INFO:     10.42.16.11:45338 - "GET / HTTP/1.1" 500 Internal Server Error
2026/09/03 09:28:16 ERROR:    Exception in ASGI application
Traceback (most recent call last):
  File "/usr/local/lib/python3.10/site-packages/mlflow/server/fastapi_app.py", line 78, in __call__
    await anyio.to_thread.run_sync(self.wsgi, environ, self.start_response)
  File "/usr/local/lib/python3.10/site-packages/anyio/to_thread.py", line 65, in run_sync
    return await get_async_backend().run_sync_in_worker_thread(
  File "/usr/local/lib/python3.10/site-packages/anyio/_backends/_asyncio.py", line 2706, in run_sync_in_worker_thread
    return await future
  File "/usr/local/lib/python3.10/site-packages/anyio/_backends/_asyncio.py", line 1100, in run
    result = context.run(func, *args)
  File "/usr/local/lib/python3.10/site-packages/starlette/middleware/wsgi.py", line 150, in wsgi
    for chunk in self.app(environ, start_response):
  File "/usr/local/lib/python3.10/site-packages/flask/app.py", line 1536, in __call__
    return self.wsgi_app(environ, start_response)
  File "/usr/local/lib/python3.10/site-packages/flask/app.py", line 1518, in wsgi_app
    return response(environ, start_response)
  File "/usr/local/lib/python3.10/site-packages/werkzeug/wrappers/response.py", line 577, in __call__
    start_response(status, headers)
  File "/usr/local/lib/python3.10/site-packages/starlette/middleware/wsgi.py", line 136, in start_response
    anyio.from_thread.run(
  File "/usr/local/lib/python3.10/site-packages/anyio/_lazyimport.py", line 41, in __getattr__
    raise AttributeError(
AttributeError: module 'anyio' has no attribute 'from_thread'

The above exception was the direct cause of the following exception:

  + Exception Group Traceback (most recent call last):
  |   File "/usr/local/lib/python3.10/site-packages/uvicorn/protocols/http/httptools_impl.py", line 409, in run_asgi
  |     result = await app(  # type: ignore[func-returns-value]
  |   File "/usr/local/lib/python3.10/site-packages/uvicorn/middleware/proxy_headers.py", line 60, in __call__
  |     return await self.app(scope, receive, send)
  |   File "/usr/local/lib/python3.10/site-packages/fastapi/applications.py", line 1160, in __call__
  |     await super().__call__(scope, receive, send)
  |   File "/usr/local/lib/python3.10/site-packages/starlette/applications.py", line 90, in __call__
  |     await self.middleware_stack(scope, receive, send)
  |   File "/usr/local/lib/python3.10/site-packages/starlette/middleware/errors.py", line 186, in __call__
  |     raise exc
  |   File "/usr/local/lib/python3.10/site-packages/starlette/middleware/errors.py", line 164, in __call__
  |     await self.app(scope, receive, _send)
  |   File "/usr/local/lib/python3.10/site-packages/starlette/middleware/base.py", line 193, in __call__
  |     response = await self.dispatch_func(request, call_next)
  |   File "/usr/local/lib/python3.10/site-packages/mlflow/server/fastapi_app.py", line 138, in gateway_timing_middleware
  |     return await call_next(request)
  |   File "/usr/local/lib/python3.10/site-packages/starlette/middleware/base.py", line 168, in call_next
  |     raise app_exc from app_exc.__cause__ or app_exc.__context__
  |   File "/usr/local/lib/python3.10/site-packages/starlette/middleware/base.py", line 144, in coro
  |     await self.app(scope, receive_or_disconnect, send_no_error)
  |   File "/usr/local/lib/python3.10/site-packages/starlette/middleware/base.py", line 193, in __call__
  |     response = await self.dispatch_func(request, call_next)
  |   File "/usr/local/lib/python3.10/site-packages/mlflow/server/fastapi_app.py", line 123, in workspace_context_middleware
  |     response = await call_next(request)
  |   File "/usr/local/lib/python3.10/site-packages/starlette/middleware/base.py", line 168, in call_next
  |     raise app_exc from app_exc.__cause__ or app_exc.__context__
  |   File "/usr/local/lib/python3.10/site-packages/starlette/middleware/base.py", line 144, in coro
  |     await self.app(scope, receive_or_disconnect, send_no_error)
  |   File "/usr/local/lib/python3.10/site-packages/mlflow/server/fastapi_security.py", line 59, in __call__
  |     return await self.app(scope, receive, send)
  |   File "/usr/local/lib/python3.10/site-packages/starlette/middleware/cors.py", line 88, in __call__
  |     await self.app(scope, receive, send)
  |   File "/usr/local/lib/python3.10/site-packages/mlflow/server/fastapi_security.py", line 114, in __call__
  |     return await self.app(scope, receive, send)
  |   File "/usr/local/lib/python3.10/site-packages/mlflow/server/fastapi_security.py", line 99, in __call__
  |     await self.app(scope, receive, send_wrapper)
  |   File "/usr/local/lib/python3.10/site-packages/starlette/middleware/exceptions.py", line 63, in __call__
  |     await wrap_app_handling_exceptions(self.app, conn)(scope, receive, send)
  |   File "/usr/local/lib/python3.10/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
  |     raise exc
  |   File "/usr/local/lib/python3.10/site-packages/starlette/_exception_handler.py", line 42, in wrapped_app
  |     await app(scope, receive, sender)
  |   File "/usr/local/lib/python3.10/site-packages/fastapi/middleware/asyncexitstack.py", line 18, in __call__
  |     await self.app(scope, receive, send)
  |   File "/usr/local/lib/python3.10/site-packages/starlette/routing.py", line 660, in __call__
  |     await self.middleware_stack(scope, receive, send)
  |   File "/usr/local/lib/python3.10/site-packages/starlette/routing.py", line 680, in app
  |     await route.handle(scope, receive, send)
  |   File "/usr/local/lib/python3.10/site-packages/starlette/routing.py", line 448, in handle
  |     await self.app(scope, receive, send)
  |   File "/usr/local/lib/python3.10/site-packages/mlflow/server/fastapi_app.py", line 101, in __call__
  |     await responder(receive, send)
  |   File "/usr/local/lib/python3.10/site-packages/mlflow/server/fastapi_app.py", line 75, in __call__
  |     async with anyio.create_task_group() as task_group:
  |   File "/usr/local/lib/python3.10/site-packages/anyio/_backends/_asyncio.py", line 847, in __aexit__
  |     raise BaseExceptionGroup(
  | exceptiongroup.ExceptionGroup: unhandled errors in a TaskGroup (1 sub-exception)
  +-+---------------- 1 ----------------
    | Traceback (most recent call last):
    |   File "/usr/local/lib/python3.10/site-packages/mlflow/server/fastapi_app.py", line 78, in __call__
    |     await anyio.to_thread.run_sync(self.wsgi, environ, self.start_response)
    |   File "/usr/local/lib/python3.10/site-packages/anyio/to_thread.py", line 65, in run_sync
    |     return await get_async_backend().run_sync_in_worker_thread(
    |   File "/usr/local/lib/python3.10/site-packages/anyio/_backends/_asyncio.py", line 2706, in run_sync_in_worker_thread
    |     return await future
    |   File "/usr/local/lib/python3.10/site-packages/anyio/_backends/_asyncio.py", line 1100, in run
    |     result = context.run(func, *args)
    |   File "/usr/local/lib/python3.10/site-packages/starlette/middleware/wsgi.py", line 150, in wsgi
    |     for chunk in self.app(environ, start_response):
    |   File "/usr/local/lib/python3.10/site-packages/flask/app.py", line 1536, in __call__
    |     return self.wsgi_app(environ, start_response)
    |   File "/usr/local/lib/python3.10/site-packages/flask/app.py", line 1518, in wsgi_app
    |     return response(environ, start_response)
    |   File "/usr/local/lib/python3.10/site-packages/werkzeug/wrappers/response.py", line 577, in __call__
    |     start_response(status, headers)
    |   File "/usr/local/lib/python3.10/site-packages/starlette/middleware/wsgi.py", line 136, in start_response
    |     anyio.from_thread.run(
    |   File "/usr/local/lib/python3.10/site-packages/anyio/_lazyimport.py", line 41, in __getattr__
    |     raise AttributeError(
    | AttributeError: module 'anyio' has no attribute 'from_thread'
    +------------------------------------
2026/09/03 09:28:26 WARNING mlflow.server.fastapi_security: Rejected request with invalid Host header: 1-mlflow_server:5006
2026/09/03 09:28:26 INFO:     10.42.16.11:55710 - "GET / HTTP/1.1" 403 Forbidden

The bug hadn't come up yesterday.

[ksmdnl]

Something to do with a missmatch with uwsgi

[EmmanuelNiyonshuti]

Something to do with a missmatch with uwsgi

Yeah?, I think this might be related to what I mentioned in my comment above? #1308 (reply in thread)
though it's still not entirely clear to me where it's actually coming from, I ran Starlette's full test suite against anyio 4.15 and it passes, aside from one minor deprecation warning Kludex/starlette#3497

[agronholm]

Here is the culprit. Starlette improperly uses the anyio.to_thread module without importing it first. This happened to work previously by chance. With the lazy re-exporting in place, the module isn't available without being properly imported.
Given the situation, a workaround from our side might be warranted.

[agronholm]

I'm certain that the reason this wasn't exposed by the test suite was that something else imported the anyio.to_thread module which made that code work as a side effect.

[agronholm]

Kludex/starlette#3501

[EmmanuelNiyonshuti]

Here is the culprit. Starlette improperly uses the anyio.to_thread module without importing it first. This happened to work previously by chance. With the lazy re-exporting in place, the module isn't available without being properly imported. Given the situation, a workaround from our side might be warranted.

Makes sense to me. Just looking at anyio.from_thread alone, a github code search https://github.com/search?q=%22anyio.from_thread.%22+NOT+%22import+anyio.from_thread%22+NOT+%22from+anyio+import+from_thread%22+language%3APython&type=code turns up a ~8.8k codebases using it without an explicit import.

[agronholm]

I have a PR to address this here. Perhaps this thread should've been created as an issue too? I can convert it into one if needed.

[ganiket19]

Yes please