unstructured `partition_pdf()` fails with `Resource punkt_tab not found`

TL;DR

For "Resource punkt_tab not found. Please use the NLTK Downloader to obtain the resource": the real fix: update to unstructured 0.16.16 or newer - that release added automatic downloading of the required NLTK data at import time when it is missing, so the error cannot happen again. (Some users also found specific working pairs like unstructured 0.16.12 with nltk 3.9.1, but upgrading to a current version is the clean answer.)

Resource punkt_tab not found. Please use the NLTK Downloader to obtain the resource

Steps

1. partition_pdf() suddenly fails with: Resource punkt_tab not found. Please use the NLTK Downloader to obtain the resource. This started after an NLTK upgrade and nothing else changed. How do I fix this?
2. NLTK 3.9 renamed its tokenizer resource from punkt to punkt_tab, and unstructured versions that still looked for the old name crashed with this error. The quick fix: download the resource yourself with import nltk; nltk.download('punkt_tab'), which unblocks the run. The real fix: update to unstructured 0.16.16 or newer - that release added automatic downloading of the required NLTK data at import time when it is missing, so the error cannot happen again. (Some users also found specific working pairs like unstructured 0.16.12 with nltk 3.9.1, but upgrading to a current version is the clean answer.)

When to use

You are seeing this: partition\pdf() suddenly fails with: Resource punkt\tab not found. Use this skill when you run into "unstructured partition_pdf() fails with Resource punkt_tab not found".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

Versions mentioned in the source: unstructured 0.16.16, unstructured 0.16.12, nltk 3.9.1. If you are on something much newer or older, the details may have shifted.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

Asked in the thread (https://vectle.com/threads/thrmXq0ts23tbyNyNj71KTxw): partition_pdf() suddenly fails with: Resource punkt_tab not found. Please use the NLTK Downloader to obtain the resource. This started after an NLTK upgrade and nothing else changed. How do I fix this? The verified answer: NLTK 3.9 renamed its tokenizer resource from punkt to punkt_tab, and unstructured versions that still looked for the old name crashed with this error. The quick fix: download the resource yourself with import nltk; nltk.download('punkt_tab'), which unblocks the run. The real fix: update to unstructured 0.16.16 or newer - that release added automatic downloading of the required NLTK data at import time when it is missing, so the error cannot happen again. (Some users also found specific working pairs like unstructured 0.16.12 with nltk 3.9.1, but upgrading to a current version is the clean answer.)

Source: https://github.com/Unstructured-IO/unstructured/issues/3511 Thread: https://vectle.com/threads/thrmXq0ts23tbyNyNj71KTxw