Python 3.12 Import Error in Vercel but Works Locally

Expected Behavior

The application should run on Vercel as it does locally on my machine with Python 3.12.8.

Steps to Reproduce

Deploy a FastAPI application to Vercel
Application fails during initialization
Error trace shows an import issue with collections.Sequence

Full Error Stack

odule>
from .applications import FastAPI as FastAPI
File "/var/task/fastapi/applications.py", line 16, in <module>
from fastapi import routing
File "/var/task/fastapi/routing.py", line 24, in <module>
from fastapi import params
File "/var/task/fastapi/params.py", line 5, in <module>
from fastapi.openapi.models import Example
File "/var/task/fastapi/openapi/models.py", line 4, in <module>
from fastapi._compat import (
File "/var/task/fastapi/_compat.py", line 21, in <module>
from fastapi.exceptions import RequestErrorModel
File "/var/task/fastapi/exceptions.py", line 3, in <module>
from pydantic import BaseModel, create_model
File "/var/task/pydantic/__init__.py", line 421, in __getattr__
module = import_module(module_name, package=package)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/var/lang/lib/python3.12/importlib/__init__.py", line 90, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/var/task/pydantic/main.py", line 34, in <module>
from ._internal import (
File "/var/task/pydantic/_internal/_model_construction.py", line 25, in <module>
from ._generate_schema import GenerateSchema
File "/var/task/pydantic/_internal/_generate_schema.py", line 10, in <module>
import pathlib
File "/var/task/pathlib.py", line 10, in <module>
from collections import Sequence
ImportError: cannot import name 'Sequence' from 'collections' (/var/lang/lib/python3.12/collections/__init__.py)
Python process exited with exit status: 1. The logs above can help with debugging the issue.
Traceback (most recent call last):
File "/var/task/vc__handler__python.py", line 14, in <module>
__vc_spec.loader.exec_module(__vc_module)
File "<frozen importlib._bootstrap_external>", line 995, in exec_module
File "<frozen importlib._bootstrap>", line 488, in _call_with_frames_removed
File "/var/task/src/main_vercel.py", line 1, in <module>
from fastapi import FastAPI, Request, WebSocket
File "/var/task/fastapi/__init__.py", line 7, in <module>
from .applications import FastAPI as FastAPI
File "/var/task/fastapi/applications.py", line 16, in <module>
from fastapi import routing
File "/var/task/fastapi/routing.py", line 24, in <module>
from fastapi import params
File "/var/task/fastapi/params.py", line 5, in <module>
from fastapi.openapi.models import Example
File "/var/task/fastapi/openapi/models.py", line 4, in <module>
from fastapi._compat import (
File "/var/task/fastapi/_compat.py", line 21, in <module>
from fastapi.exceptions import RequestErrorModel
File "/var/task/fastapi/exceptions.py", line 3, in <module>
from pydantic import BaseModel, create_model
File "/var/task/pydantic/__init__.py", line 421, in __getattr__
module = import_module(module_name, package=package)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/var/lang/lib/python3.12/importlib/__init__.py", line 90, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/var/task/pydantic/main.py", line 34, in <module>
from ._internal import (
File "/var/task/pydantic/_internal/_model_construction.py", line 25, in <module>
from ._generate_schema import GenerateSchema
File "/var/task/pydantic/_internal/_generate_schema.py", line 10, in <module>
import pathlib
File "/var/task/pathlib.py", line 10, in <module>
from collections import Sequence
ImportError: cannot import name 'Sequence' from 'collections' (/var/lang/lib/python3.12/collections/__init__.py)
Python process exited with exit status: 1. The logs above can help with debugging the issue.

Project Information

Framework: FastAPI
Python Version: 3.12.8
Environment: Vercel Serverless Functions
Key Dependencies:
```
fastapi==0.115.8
pydantic==2.10.6
```

Questions

How can I recreate Vercel's Python 3.12 environment locally to debug this issue?
Are there any known compatibility issues with Python 3.12 in Vercel's environment?
What's the recommended way to ensure dependency versions match between local and Vercel environments?

Any guidance would be greatly appreciated!

Traceback (most recent call last): File "/var/task/vc__handler__python.py", line 14, in <module> __vc_spec.loader.exec_module(__vc_module) File "<frozen importlib._bootstrap_external>", line 995, in exec_module File "<frozen importlib._bootstrap>", line 488, in _call_with_frames_removed File "/var/task/src/main_vercel.py", line 1, in <module> from fastapi import FastAPI, Request, WebSocket File "/var/task/fastapi/__init__.py", line 7, in <module> from .applications import FastAPI as FastAPI File "/var/task/fastapi/applications.py", line 16, in <module> from fastapi import routing File "/var/task/fastapi/routing.py", line 24, in <module> from fastapi import params File "/var/task/fastapi/params.py", line 5, in <module> from fastapi.openapi.models import Example File "/var/task/fastapi/openapi/models.py", line 4, in <module> from fastapi._compat import ( File "/var/task/fastapi/_compat.py", line 21, in <module> from fastapi.exceptions import RequestErrorModel File "/var/task/fastapi/exceptions.py", line 3, in <module> from pydantic import BaseModel, create_model File "<frozen importlib._bootstrap>", line 1412, in _handle_fromlist File "/var/task/pydantic/__init__.py", line 421, in __getattr__ module = import_module(module_name, package=package) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/var/lang/lib/python3.12/importlib/__init__.py", line 90, in import_module return _bootstrap._gcd_import(name[level:], package, level) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/var/task/pydantic/main.py", line 34, in <module> from ._internal import ( File "/var/task/pydantic/_internal/_model_construction.py", line 25, in <module> from ._generate_schema import GenerateSchema File "/var/task/pydantic/_internal/_generate_schema.py", line 42, in <module> from uuid import UUID File "/var/task/uuid.py", line 138 if not 0 <= time_low < 1<<32L: ^ SyntaxError: invalid decimal literal Python process exited with exit status: 1. The logs above can help with debugging the issue.

odule> from .applications import FastAPI as FastAPI File "/var/task/fastapi/applications.py", line 16, in <module> from fastapi import routing File "/var/task/fastapi/routing.py", line 24, in <module> from fastapi import params File "/var/task/fastapi/params.py", line 5, in <module> from fastapi.openapi.models import Example File "/var/task/fastapi/openapi/models.py", line 4, in <module> from fastapi._compat import ( File "/var/task/fastapi/_compat.py", line 21, in <module> from fastapi.exceptions import RequestErrorModel File "/var/task/fastapi/exceptions.py", line 3, in <module> from pydantic import BaseModel, create_model File "/var/task/pydantic/__init__.py", line 421, in __getattr__ module = import_module(module_name, package=package) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/var/lang/lib/python3.12/importlib/__init__.py", line 90, in import_module return _bootstrap._gcd_import(name[level:], package, level) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/var/task/pydantic/main.py", line 34, in <module> from ._internal import ( File "/var/task/pydantic/_internal/_model_construction.py", line 25, in <module> from ._generate_schema import GenerateSchema File "/var/task/pydantic/_internal/_generate_schema.py", line 10, in <module> import pathlib File "/var/task/pathlib.py", line 10, in <module> from collections import Sequence ImportError: cannot import name 'Sequence' from 'collections' (/var/lang/lib/python3.12/collections/__init__.py) Python process exited with exit status: 1. The logs above can help with debugging the issue. Traceback (most recent call last): File "/var/task/vc__handler__python.py", line 14, in <module> __vc_spec.loader.exec_module(__vc_module) File "<frozen importlib._bootstrap_external>", line 995, in exec_module File "<frozen importlib._bootstrap>", line 488, in _call_with_frames_removed File "/var/task/src/main_vercel.py", line 1, in <module> from fastapi import FastAPI, Request, WebSocket File "/var/task/fastapi/__init__.py", line 7, in <module> from .applications import FastAPI as FastAPI File "/var/task/fastapi/applications.py", line 16, in <module> from fastapi import routing File "/var/task/fastapi/routing.py", line 24, in <module> from fastapi import params File "/var/task/fastapi/params.py", line 5, in <module> from fastapi.openapi.models import Example File "/var/task/fastapi/openapi/models.py", line 4, in <module> from fastapi._compat import ( File "/var/task/fastapi/_compat.py", line 21, in <module> from fastapi.exceptions import RequestErrorModel File "/var/task/fastapi/exceptions.py", line 3, in <module> from pydantic import BaseModel, create_model File "/var/task/pydantic/__init__.py", line 421, in __getattr__ module = import_module(module_name, package=package) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/var/lang/lib/python3.12/importlib/__init__.py", line 90, in import_module return _bootstrap._gcd_import(name[level:], package, level) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/var/task/pydantic/main.py", line 34, in <module> from ._internal import ( File "/var/task/pydantic/_internal/_model_construction.py", line 25, in <module> from ._generate_schema import GenerateSchema File "/var/task/pydantic/_internal/_generate_schema.py", line 10, in <module> import pathlib File "/var/task/pathlib.py", line 10, in <module> from collections import Sequence ImportError: cannot import name 'Sequence' from 'collections' (/var/lang/lib/python3.12/collections/__init__.py) Python process exited with exit status: 1. The logs above can help with debugging the issue.