Uncaught ModuleNotFoundError in environment.py line 18

[galihaziz]

Aider version: 0.86.2
Python version: 3.10.9
Platform: Windows-10-10.0.26200-SP0
Python implementation: CPython
Virtual environment: No
OS: Windows 10 (64bit)
Git version: git version 2.49.0.windows.1

An uncaught exception occurred:

Traceback (most recent call last):
  File "runpy.py", line 196, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "__main__.py", line 5, in <module>
    sys.exit(main())
  File "main.py", line 822, in main
    main_model = models.Model(
  File "models.py", line 339, in __init__
    res = self.validate_environment()
  File "models.py", line 736, in validate_environment
    res = litellm.validate_environment(model)
  File "llm.py", line 27, in __getattr__
    self._load_litellm()
  File "llm.py", line 37, in _load_litellm
    self._lazy_module = importlib.import_module("litellm")
  File "__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1050, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1027, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1006, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 688, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 883, in exec_module
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "__init__.py", line 1137, in <module>
    from .main import *  # type: ignore
  File "main.py", line 86, in <module>
    from litellm.litellm_core_utils.litellm_logging import Logging as LiteLLMLoggingObj
  File "litellm_logging.py", line 56, in <module>
    from litellm.integrations.arize.arize import ArizeLogger
  File "__init__.py", line 10, in <module>
    from .arize_phoenix_prompt_manager import ArizePhoenixPromptManager
  File "arize_phoenix_prompt_manager.py", line 8, in <module>
    from jinja2 import DictLoader, Environment, select_autoescape
  File "__init__.py", line 9, in <module>
    from .environment import Environment as Environment
  File "environment.py", line 18, in <module>
    from .compiler import CodeGenerator
ModuleNotFoundError: No module named 'jinja2.compiler'

[PierrunoYT]

The traceback points away from aider: ModuleNotFoundError: No module named 'jinja2.compiler'
means the installed jinja2 is broken, usually a partial or interrupted upgrade, or a file or
directory named jinja2.py / jinja2/ in the working directory shadowing the real package.
Reinstalling into a clean virtual environment should clear it.

What does look like a defect is the presentation. litellm is imported lazily, so any
ImportError from it or from its dependencies escapes as an uncaught exception, and the crash
handler then invites the user to file a bug against aider for a problem in their own environment,
which is how this issue came to be.

In Patch (a fork of aider) I wrapped the lazy import so it
raises a dedicated error carrying an actionable message — what failed, that it is the Python
environment rather than the tool, the shadowing file to look for, and the reinstall commands —
and made the crash handler print that instead of a traceback and the issue form. Everything else
still reports as before. Happy to open a PR here if that would be useful.

[MilkyWay008]

The No module named 'jinja2.compiler' in environment.py line 18 is a broken jinja2 install, not an aider bug: the top-level package imports but its compiler submodule is missing, which on Windows usually means a partial or interrupted upgrade (or a stray jinja2.py/jinja2/ folder in the working directory shadowing the real package). Reinstall it clean: pip install --upgrade --force-reinstall jinja2, then verify with python -c "import jinja2.compiler" (no error = fixed). If you're not using a venv, I'd move aider into one and reinstall aider-chat there; that isolates the mess for good. Oh also, btw, I built a portable Hermes OTG and run it off USB as my rescue agent, https://github.com/MilkyWay008/Hermes-OTG, handy when a tool's Python env goes sideways.