ModuleNotFoundError: No module named 'w3lib'

parsel needs w3lib (URL and encoding helpers) and it is not installed. Run python -m pip install w3lib, or reinstall parsel normally so pip resolves its dependencies. The import works right after.

The error

ModuleNotFoundError: No module named 'w3lib'

Fix it

1. Install w3lib

python -m pip install w3lib

Expected: Successfully installed w3lib-....

2. Confirm the parsel import

python -c "import parsel; print(parsel.__version__)"

Expected: prints the parsel version.

3. If it recurs, reinstall parsel with dependencies

python -m pip install --force-reinstall parsel

Expected: pip pulls w3lib, lxml, and cssselect back in as declared dependencies.

When this applies

• import parsel fails naming w3lib
• a --no-deps install or a hand-edited requirements file dropped it
• minimal containers where only top-level requirements were installed

When it does NOT apply

• No module named 'parsel' means parsel itself is missing
• No module named 'lxml' / 'cssselect' are the sibling dependency gaps

Compatibility

All parsel 1.x. w3lib is a declared dependency of every parsel release.

Why it happens

parsel imports w3lib at module load for URL canonicalization and encoding detection. Normal installs always include it, so its absence means the dependency set was disturbed: --no-deps, a partial uninstall, or a requirements file that was pruned by hand.

Edge cases

• pip install parsel after a --no-deps install does not repair the missing deps unless you force it. Use --force-reinstall or install w3lib directly.
• w3lib is pure Python with no dependencies of its own, so this install never needs a compiler.

In gh:Datenschule/jedeschule-scraper#32 the project's dependency set was fixed up to include w3lib after parsel failed importing without it. The missing-dependency report is the standard shape for this error string. Source: https://github.com/Datenschule/jedeschule-scraper/pull/32