Troubleshooting

This page describes common problems that may happen when setting up or running the project.

The goal is to help you slow down, read the error, and check the most likely cause.

General rule

When something fails, start with:

git status
uv --version
uv sync
uv run ruff check .
uv run ruff format --check .
uv run rumdl check .
uv run mkdocs build --strict
uv run pytest --cov=text_toolkit --cov-report=term-missing
uv run mypy

Do not change many things at once.

Read the first error message carefully.

Fix one problem, then run the checks again.

`uv` command not found

Problem

You run:

uv --version

and the terminal says that uv is not found.

Possible cause

uv is not installed, or the terminal does not see it in PATH.

Fix

Install uv.

macOS and Linux:

curl -LsSf https://astral.sh/uv/install.sh | sh

Windows PowerShell:

powershell -ExecutionPolicy ByPass -c "irm https://astral.sh/uv/install.ps1 | iex"

Then restart the terminal and check again:

uv --version

Python version is missing

Problem

uv reports that the requested Python version is not installed.

Possible cause

The project uses .python-version, but that Python version is not available locally yet.

Fix

Run:

uv python install

Then sync the environment:

uv sync

Virtual environment was not created

Problem

You expected a .venv/ directory, but it does not exist.

Possible cause

The project environment has not been synchronized yet.

Fix

Run:

uv sync

Expected result:

.venv/

The .venv/ directory is local.

Do not commit it to Git.

Tests cannot import the package

Problem

Running tests fails with an import error, for example:

ModuleNotFoundError: No module named 'text_toolkit'

Possible cause

The project uses a src/ layout, but it was not installed into the environment.

Fix

Check that pyproject.toml contains a build system:

[build-system]
requires = ["uv_build>=0.12.19,<0.13"]
build-backend = "uv_build"

Then run:

uv sync
uv run pytest

The sync output should show that text-toolkit was built and installed from the local project.

pytest is not found

Problem

You run:

uv run pytest

and pytest is not available.

Possible cause

Development dependencies were not installed or pytest is missing from the development dependency group.

Fix

Check that pyproject.toml contains something similar to:

[dependency-groups]
dev = [
    "pytest>=9.0.3",
    "ruff>=0.15.12",
]

Then run:

uv sync
uv run pytest

If pytest is missing, add it:

uv add --group dev pytest

Commit both:

pyproject.toml
uv.lock

Ruff is not found

Problem

You run:

uv run ruff check .

and Ruff is not available.

Possible cause

Ruff is not installed as a development dependency.

Fix

Add Ruff:

uv add --group dev ruff

Then run:

uv run ruff check .
uv run ruff format --check .

Commit both:

pyproject.toml
uv.lock

Formatting check fails

Problem

This command fails:

uv run ruff format --check .

Possible cause

Some files are not formatted according to Ruff.

Fix

Run:

uv run ruff format .

Then check again:

uv run ruff check .
uv run ruff format --check .
uv run rumdl check .
uv run mkdocs build --strict
uv run pytest --cov=text_toolkit --cov-report=term-missing
uv run mypy

Ruff linting fails

Problem

This command fails:

uv run ruff check .

Possible cause

Ruff found a linting issue.

Examples:

unused import,
unsorted imports,
undefined name,
outdated syntax,
suspicious pattern.

Fix

Read the Ruff message.

If Ruff offers an automatic fix, you can try:

uv run ruff check . --fix

Then run all checks again:

uv run ruff check .
uv run ruff format --check .
uv run rumdl check .
uv run mkdocs build --strict
uv run pytest --cov=text_toolkit --cov-report=term-missing
uv run mypy

Do not blindly apply fixes without reviewing the diff.

Check:

git diff

mypy is missing or type checking fails

Problem

This command is unavailable or reports a type error:

uv run mypy

Possible causes

the local environment is out of sync,
mypy is missing from the development dependency group,
code does not match its type annotations.

Fix

Sync the environment first:

uv sync
uv run mypy

When adding mypy to a different project, record it as a development dependency:

uv add --group dev mypy

For a type error, read the file path, line number, and error code. Fix the code or its annotation instead of adding a broad ignore without understanding the problem.

Tests fail

Problem

This command fails:

uv run pytest

Possible cause

The code behavior does not match the expected behavior in tests.

Fix

Read the failing test name first.

Then read the assertion error.

Useful command:

uv run pytest -v

If needed, run one test file:

uv run pytest tests/test_text_stats.py

Fix the code or the test, depending on what is actually wrong.

Then run:

uv run ruff check .
uv run ruff format --check .
uv run rumdl check .
uv run mkdocs build --strict
uv run pytest --cov=text_toolkit --cov-report=term-missing
uv run mypy

Coverage reporting fails

Problem

Tests may pass without coverage, but this command fails:

uv run pytest --cov=text_toolkit --cov-report=term-missing

Possible causes

pytest-cov is missing from the development dependency group,
the local environment is out of sync,
the package name passed to --cov is incorrect,
coverage configuration is invalid.

Fix

Sync dependencies and retry:

uv sync
uv run pytest --cov=text_toolkit --cov-report=term-missing

Check that pyproject.toml contains pytest-cov and the [tool.coverage.run] section. A lower percentage by itself does not fail this project because no fail_under threshold is configured.

Markdown linting fails

Problem

This command reports one or more rule violations:

uv run rumdl check .

Possible causes

a heading level was skipped,
a list or code fence is missing surrounding blank lines,
a fenced code block has no language identifier,
Markdown structure or style is inconsistent,
a deliberate project pattern needs a narrow exception.

Fix

Read the rule identifier and inspect the reported line. Fix the structure when it is genuinely inconsistent.

For automatically fixable issues, you may run:

uv run rumdl check --fix .
git diff

Review every automatic change. Configure an exception only when the existing Markdown is intentional and the reason can be explained.

MkDocs build fails

Problem

The strict documentation build exits with an error:

uv run mkdocs build --strict

Possible causes

a page is missing from mkdocs.yml,
a navigation target does not exist,
a document link or heading anchor is incorrect,
MkDocs emitted a warning that strict mode treats as an error.

Fix

Read the first warning, correct the referenced page or navigation entry, and run the strict build again.

For visual review, start the local server:

uv run mkdocs serve

If port 8000 is already in use, choose another address:

uv run mkdocs serve --dev-addr 127.0.0.1:8001

GitHub Pages deployment fails

Problem

The Documentation workflow builds the site but cannot deploy it.

Possible causes

Pages is not configured to use GitHub Actions as its source,
the deploy job is missing pages: write or id-token: write,
the build job did not upload the github-pages artifact,
an environment protection rule is waiting for approval,
GitHub Pages or Actions is temporarily unavailable.

Fix

Open Settings → Pages and confirm that Source is GitHub Actions. Then inspect the first useful error in the failed Deploy documentation job.

Do not commit site/ or create a gh-pages branch to work around this workflow. Fix the configuration in a new pull request and rerun the deployment after it reaches main.

If the workflow passed but the site still shows old content, open the deployment URL reported by the job and confirm that the expected commit triggered the run.

A pre-commit hook fails or changes files

Problem

Git stops a commit because a hook failed or modified a file.

Possible causes

a file contains trailing whitespace or invalid YAML or TOML,
unresolved merge conflict markers remain,
Ruff found or fixed a Python issue,
a hook changed a file that must be staged again.

Fix

Review both the hook output and the resulting diff:

git diff
uv run pre-commit run --all-files

If a hook fixed a file, stage the reviewed change and try the commit again. Do not bypass the hook merely because it changed a file.

If pre-commit itself is missing, sync the development environment:

uv sync
uv run pre-commit install

`uv.lock` is out of sync

Problem

CI fails during:

uv sync --locked --group dev

Possible cause

pyproject.toml changed, but uv.lock was not updated.

CI uses uv sync --locked --group dev because it should verify the committed project state and explicitly install the development tools, not silently update files.

Fix

Run locally:

uv sync

or:

uv lock

Then commit:

pyproject.toml
uv.lock

Run checks again:

uv run ruff check .
uv run ruff format --check .
uv run rumdl check .
uv run mkdocs build --strict
uv run pytest --cov=text_toolkit --cov-report=term-missing
uv run mypy

`.venv/` was committed by mistake

Problem

The pull request contains many files from:

.venv/

Possible cause

The virtual environment was added to Git accidentally.

Fix

Make sure .gitignore contains:

.venv/

Remove .venv/ from Git tracking:

git rm -r --cached .venv

Then commit the cleanup:

git add .gitignore
git commit -m "chore: stop tracking virtual environment"

The local .venv/ directory can still exist on your machine.

It should just not be tracked by Git.

Cache directories were committed

Problem

The pull request contains files such as:

__pycache__/
.pytest_cache/
.ruff_cache/
.mypy_cache/

Possible cause

Generated cache files were added to Git accidentally.

Fix

Make sure .gitignore contains:

__pycache__/
.pytest_cache/
.ruff_cache/
.mypy_cache/

Remove cached files from Git tracking if needed:

git rm -r --cached __pycache__ .pytest_cache .ruff_cache .mypy_cache

Some directories may not exist. That is fine.

Then commit the cleanup.

Git says working tree is not clean

Problem

You run:

git status

and see modified or untracked files.

Possible cause

You changed files locally, generated files appeared, or formatting changed files.

Fix

Review the changes:

git diff

For staged changes:

git diff --staged

If the changes are correct, commit them.

If a generated file appears, add it to .gitignore or remove it from Git tracking.

Do not commit files you do not understand.

Git branch is behind main

Problem

Your branch is outdated compared to main.

Possible cause

Other pull requests were merged after you created your branch.

Fix

Update main:

git switch main
git pull

Then update your branch.

For a beginner-friendly workflow, the simplest option is often to create a fresh branch from the updated main and reapply a small change.

If the branch contains more work, use Git carefully and ask for help before rewriting history.

Pull request contains unrelated files

Problem

The pull request shows files that are not related to the change.

Possible cause

Files were edited accidentally, generated files were committed, or the branch was used for more than one task.

Fix

Check:

git status
git diff

Remove unrelated changes before committing.

If unrelated changes are already committed, consider making a new clean branch and copying only the intended changes.

Small pull requests are easier to fix.

CI fails but local checks pass

Problem

Local checks pass, but GitHub Actions fails.

Possible causes

uncommitted local changes,
missing uv.lock update,
different Python version,
platform-specific behavior,
stale branch,
CI configuration issue.

Fix

Start with:

git status
uv sync
uv run ruff check .
uv run ruff format --check .
uv run rumdl check .
uv run mkdocs build --strict
uv run pytest --cov=text_toolkit --cov-report=term-missing
uv run mypy

Then check whether these files were committed if they changed:

pyproject.toml
uv.lock
.github/workflows/ci.yml

If CI still fails, open the failed GitHub Actions run and read the first failing step.

Local checks fail after pulling main

Problem

The project worked before, but after:

git pull

local checks fail.

Possible cause

New changes modified dependencies, tool configuration, tests, or source code.

Fix

Run:

uv sync
uv run ruff check .
uv run ruff format --check .
uv run rumdl check .
uv run mkdocs build --strict
uv run pytest --cov=text_toolkit --cov-report=term-missing
uv run mypy

If dependencies changed, uv sync is the important first step.

Markdown looks wrong on GitHub

Problem

A Markdown file looks fine locally, but strange on GitHub.

Possible causes

broken code fence,
missing blank line,
wrong indentation,
nested code blocks,
malformed list,
broken link.

Fix

Review the rendered Markdown in the pull request.

Also inspect the raw diff.

Common things to check:

every code fence starts and ends with triple backticks,
lists have blank lines before code blocks,
links use correct relative paths,
headings are in the right order.

Link in README is broken

Problem

A README link returns 404 or points to the wrong file.

Possible cause

The file path is wrong, the file was renamed, or the link uses the wrong relative path.

Fix

For files inside docs/, use paths like:

[Glossary](docs/glossary.md)

For links from one file inside docs/ to another file inside docs/, use:

[Glossary](glossary.md)

Check links after opening the pull request.

A command works in PowerShell but not in Bash

Problem

A command works in one shell but not another.

Possible cause

Some commands are shell-specific.

For example:

mkdir -p src/example_project tests
touch src/example_project/__init__.py

works in Bash, but PowerShell may need:

New-Item -ItemType Directory -Force src/example_project
New-Item -ItemType Directory -Force tests
New-Item -ItemType File -Force src/example_project/__init__.py

Fix

Use the command version for your shell.

This guide often shows both Bash and PowerShell examples when file creation commands differ.

When in doubt

Use this sequence:

git status
uv sync
uv run ruff check .
uv run ruff format --check .
uv run rumdl check .
uv run mkdocs build --strict
uv run pytest --cov=text_toolkit --cov-report=term-missing
uv run mypy

Then:

read the first error,
fix one thing,
run the checks again,
review the diff,
commit only related changes.

Rule of thumb

Most setup problems are caused by one of these:

environment not synced,
missing dependency,
stale lockfile,
wrong branch,
generated files committed by mistake,
local changes not committed,
command run from the wrong directory.

Start with the simple checks before changing configuration.

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Troubleshooting

General rule

uv command not found

Problem

Possible cause

Fix

Python version is missing

Problem

Possible cause

Fix

Virtual environment was not created

Problem

Possible cause

Fix

Tests cannot import the package

Problem

Possible cause

Fix

pytest is not found

Problem

Possible cause

Fix

Ruff is not found

Problem

Possible cause

Fix

Formatting check fails

Problem

Possible cause

Fix

Ruff linting fails

Problem

Possible cause

Fix

mypy is missing or type checking fails

Problem

Possible causes

Fix

Tests fail

Problem

Possible cause

Fix

Coverage reporting fails

Problem

Possible causes

Fix

Markdown linting fails

Problem

Possible causes

Fix

MkDocs build fails

Problem

Possible causes

Fix

GitHub Pages deployment fails

Problem

Possible causes

Fix

A pre-commit hook fails or changes files

Problem

Possible causes

Fix

uv.lock is out of sync

Problem

Possible cause

Fix

.venv/ was committed by mistake

Problem

Possible cause

Fix

Cache directories were committed

Problem

Possible cause

Fix

Git says working tree is not clean

Problem

Possible cause

Fix

Git branch is behind main

Problem

`uv` command not found

`uv.lock` is out of sync

`.venv/` was committed by mistake