ImportError: No module named merge_labs – Error/Bug Definition

The Python interpreter raises ImportError: No module named 'merge_labs' when the requested package cannot be located in sys.path. This typically halts execution at import time and prevents any downstream code from running.

Root Cause Analysis

• Missing package installation: The merge_labs wheel/pip package was never installed in the current environment.
• Virtual environment mismatch: The script runs inside a virtualenv that does not share the global site‑packages where merge_labs was installed.
• Incorrect package name: The project’s requirements.txt references a typo (e.g., merge-labs instead of merge_labs).
• Path manipulation: Custom sys.path.append() calls overwrite the original search path, hiding the installed module.
• Corrupted installation: Partial install left behind an empty merge_labs directory, causing the import to fail.

Diagnostic Steps

1. Run python -m pip show merge_labs to verify the package is installed.
2. Check sys.path inside a REPL:

   import sys; print(sys.path)

3. Inspect the active virtual environment with which python (Unix) or where python (Windows).
4. Search for duplicate merge_labs directories in the project tree.

   find . -type d -name "merge_labs"

Fix Implementation

Option 1 – Install the missing package (stable release)

Activate the correct environment and run:

python -m pip install "merge_labs==1.4.2"

For the official stable documentation, see the Stable Version guide.

Option 2 – Switch to an alternative library

If merge_labs is deprecated, replace it with the maintained brain_interface package:

python -m pip install brain_interface

Reference the Alternative Library documentation for migration steps.

Option 3 – Correct the import path

Remove any manual sys.path modifications that overwrite defaults. Ensure the project’s root is added correctly:

import os, sys
sys.path.append(os.path.abspath(os.path.join(os.path.dirname(__file__), "..")))
from merge_labs import core

Option 4 – Reinstall a corrupted package

Force‑reinstall to repair a broken distribution:

python -m pip uninstall merge_labs -y && python -m pip install merge_labs

Verification

1. Restart the interpreter and run import merge_labs. No exception should be raised.
2. Execute the original script’s entry point; it should progress past the import line.
3. Run the test suite (if any) to confirm full functionality.

   pytest -q

Preventive Measures

• Pin the exact version in requirements.txt (e.g., merge_labs==1.4.2).
• Include a post‑install script that validates the import.

  python -c "import merge_labs" || echo 'Import failed'

• Document the virtual‑environment activation steps in the project README.