37 posts tagged with "Python"

uv add installs a package into your project and records it, all in one step. It updates pyproject.toml, writes the exact versions to uv.lock, and installs everything into the project's own environment. This guide explains the command's syntax first, then adds a package and two development tools to a small hello-world project, with real output from uv 0.13.8.

uv init turns a folder into a complete Python project in about a second: a pyproject.toml, a pinned Python version, a source folder, a .gitignore and a Git repository. This guide explains the command's syntax first, then creates a small hello-world project and walks through every file uv writes, with real output from uv 0.13.8.

mean_squared_error(y_true, y_pred, squared=False) is how many tutorials calculate RMSE. In scikit-learn 1.9.1 it fails with TypeError: got an unexpected keyword argument 'squared': the argument was deprecated in scikit-learn 1.4 and has since been removed. root_mean_squared_error() does the same calculation.

An MLflow training run printed seven urllib3 retry warnings over about four minutes, then failed with MlflowException: API request to … failed with exception … Max retries exceeded … [Errno 61] Connection refused. Nothing was listening at the tracking URI. MLflow's client retries for minutes before it gives up, which makes a missing server look like a hang. Starting the server fixed it, and MLFLOW_HTTP_REQUEST_MAX_RETRIES makes the same mistake fail in seconds.

pytest passed all 12 tests of a project that logs to MLflow, then printed a warnings summary: SADeprecationWarning: The ``noload`` loader strategy is deprecated. It comes from MLflow 3.18.0's SQL tracking store meeting SQLAlchemy 2.1, and MLflow fixed it the day after 3.18.0 shipped. Until a release includes the fix, one filterwarnings line hides exactly this warning in your tests.

Pressing Ctrl+C to stop MLflow 3.18.0's tracking server printed Exception ignored on threading shutdown: and a KeyboardInterrupt traceback from Python's own threading.py. Nothing crashed: the server stopped cleanly, and the message comes from its background job runner being interrupted at exit. If you don't use MLflow's server jobs, MLFLOW_SERVER_ENABLE_JOB_EXECUTION=false makes it go away.

Starting MLflow 3.18.0's tracking server printed StarletteDeprecationWarning: starlette.middleware.wsgi is deprecated four times. Nothing was wrong with my setup: the warning comes from MLflow's own code meeting Starlette 1.10.0, and the server works. One PYTHONWARNINGS filter hides this warning, and only this one, until MLflow changes its code.

A Python script stopped with ModuleNotFoundError: No module named 'PIL'. The obvious fix, pip install PIL, fails as well, because the package isn't called that: you import PIL, and you install Pillow. Here's how the error came up, what the failing fix looks like, and the install that works.

A Python script on my Mac couldn't open an HTTPS address: ssl.SSLCertVerificationError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate. curl opened the same address without a problem. Python from python.org brings its own OpenSSL, which doesn't use the Mac's certificates, and the fix is a script that comes with it: Install Certificates.

The last part turns the Lead Qualifier into something you can change without fear. You test the whole API, every failure from Part 6 included, with a fake that stands in for Claude, so the tests run in a fraction of a second and never cost a cent. Then you add a quality gate and a README, release version 1.0.0, and look back at everything you built.