ImportError: cannot import name 'log_evaluation' from 'lightgbm'

TL;DR: log_evaluation was added in lightgbm 4.0 and your install is older. Upgrade lightgbm and the import works.

The error

ImportError: cannot import name 'log_evaluation' from 'lightgbm'

Fix it

1. Upgrade lightgbm:

   pip install -U lightgbm

   Expected: installs lightgbm 4.0 or newer.

2. Verify:

   python -c "from lightgbm import log_evaluation; print('ok')"

   Expected: prints ok.

When this applies

Use this when code does from lightgbm import log_evaluation on lightgbm below 4.0.

When it does not apply

If lightgbm is already 4.0+ and the import still fails, the install is corrupt; reinstall. If the error names a different callback, check when it was added.

Compatibility

lightgbm 4.0+. log_evaluation does not exist on 3.x.

Root cause

lightgbm 4.0 reworked the callback API and added logevaluation (and earlystopping) as importable names. Code written against 4.0+ breaks on older installs that never had the name.

Edge cases

The 4.0 upgrade also changed some parameter behaviors; run your training once to confirm metrics match expectations. If other pins force lightgbm 3.x, write the logging callback by hand instead.

GitHub issue microsoft/lightgbm#6187 reports ImportError: cannot import name 'logevaluation' from 'lightgbm' with an older lightgbm installed. The verified answer: logevaluation was introduced in lightgbm 4.0, so the import only works on 4.0+; the fix is upgrading lightgbm (pip install -U lightgbm), after which the callback imports fine. Full thread: https://github.com/microsoft/lightgbm/issues/6187