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lcpy gen resolves numbers and tags against the JSON catalog bundled with your installed version. The error means the number, name, or tag is not in that catalog. A close cousin, reported as a warning during bulk runs:
That one means the name does not match a catalog entry, most often because the name is spelled as a slug instead of snake_case.

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Reproduce

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Fix

  • Check what ships with your version: run lcpy list, or lcpy list -t <tag> for one collection. Only listed problems can be generated.
  • With -s, spell the name exactly as the repo does, underscored: two_sum, valid_palindrome. The hyphenated form (two-sum) is the LeetCode URL slug and matches nothing. Numbers via -n sidestep spelling entirely:
  • Problem added to the repo after you installed: upgrade the package, pip install --upgrade leetcode-py-sdk, then generate again.
  • Problem not in the catalog at all: it has to be scraped and added first; see Problem Creation.
Not this error? Every fix lives on Troubleshooting.
Last modified on August 31, 2026