facebookresearch/detectron2 · error · ImportError

Relative import of directories is not allowed within config

Error message

Relative import of directories is not allowed within config files. Within a config file, relative import can only import other config files.

What it means

Config files execute with a patched __import__ that only supports relative imports of other .py config files. An empty relative module path in a from . import X statement (or a bare relative import of a package) triggers this ImportError explaining that directories cannot be relatively imported from configs.

Source

Thrown at detectron2/config/lazy.py:125

       e.g. you can import file without having __init__
    2. do not cache modules globally; modifications of module states has no side effect
    3. support other storage system through PathManager, so config files can be in the cloud
    4. imported dict are turned into omegaconf.DictConfig automatically
    """
    old_import = builtins.__import__

    def find_relative_file(original_file, relative_import_path, level):
        # NOTE: "from . import x" is not handled. Because then it's unclear
        # if such import should produce `x` as a python module or DictConfig.
        # This can be discussed further if needed.
        relative_import_err = """
Relative import of directories is not allowed within config files.
Within a config file, relative import can only import other config files.
""".replace(
            "\n", " "
        )
        if not len(relative_import_path):
            raise ImportError(relative_import_err)

        cur_file = os.path.dirname(original_file)
        for _ in range(level - 1):
            cur_file = os.path.dirname(cur_file)
        cur_name = relative_import_path.lstrip(".")
        for part in cur_name.split("."):
            cur_file = os.path.join(cur_file, part)
        if not cur_file.endswith(".py"):
            cur_file += ".py"
        if not PathManager.isfile(cur_file):
            cur_file_no_suffix = cur_file[: -len(".py")]
            if PathManager.isdir(cur_file_no_suffix):
                raise ImportError(f"Cannot import from {cur_file_no_suffix}." + relative_import_err)
            else:
                raise ImportError(
                    f"Cannot import name {relative_import_path} from "
                    f"{original_file}: {cur_file} does not exist."
                )

View on GitHub (pinned to a2f4a8771a)

Solutions

Use a concrete relative config import: from .base_config import model
Import library code absolutely (full package path) instead of relatively
Ensure the name after 'import' is non-empty and refers to a .py config file

Example fix

# before (inside config)
from . import
# after
from .base_config import model

Defensive patterns

Strategy: validation

Validate before calling

import re
src = open(cfg_path).read()
for m in re.finditer(r"^\s*from\s+(\.+)([\w.]*)\s+import", src, re.M):
    assert m.group(2), "relative import with empty module path in config"

Try / catch

try:
    cfg = LazyConfig.load(path)
except ImportError as e:
    if "Relative import of directories" in str(e):
        print("rewrite relative imports in", path)
    raise

Prevention

Use explicit module names in config relative imports
Prefer absolute imports for non-config code
Keep config files flat and simple

When it happens

Trigger: Inside a LazyConfig .py file, writing 'from . import' with nothing after it, or a relative import whose module path resolves to empty after stripping dots, e.g. malformed 'from .. import' usage.

Common situations: Hand-editing relative imports in configs; converting a package module into a config file while leaving package-style relative imports; IDE auto-import inserting broken statements.

Related errors

AI-assisted analysis of facebookresearch/detectron2@a2f4a8771a (2026-08-27). Data as JSON: /api/errors/0a587827668be2f4. Report an issue: GitHub.