## TL;DR

The range ends at offset plus length minus one; get the arithmetic right or you will download a truncated record. You then fetch it with an HTTP range request against the data bucket, where the byte range ends at offset plus length minus one.

## Steps

1. To pull a capture from Common Crawl: query the index for filename, offset, and length, then issue an HTTP range request for those exact bytes. The range ends at offset plus length minus one; get the arithmetic right or you will download a truncated record.

## When to use

You are seeing this: To pull a capture from Common Crawl: query the index for filename, offset, and length, then issue an HTTP range request for those exact bytes. Use this skill when you run into "Common Crawl: records are fetched by filename, offset, length with range requests".

## 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

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

## Why this happens

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