DOI resolution failed error 404 doi.org link not found

Fixes a DOI resolution failed error 404 from doi.org when a reference link does not resolve. Use when a citation verifier hits a dead DOI, an unregistered DOI, or a malformed DOI in a reference list. Not for Crossref metadata mismatches where the DOI resolves but returns the wrong paper.

Extract the DOI exactly as stored and strip surrounding punctuation, trailing periods, and URL prefixes. Keep only the part starting with 10.

Resolve the cleaned DOI directly in a browser or with curl -I against the doi.org resolver.

Query the Crossref API for the same DOI to check registration.

If Crossref returns 404, search Crossref by the exact paper title from the reference.

Fix the reference: replace the DOI with the verified DOI from step 4, or flag the entry for human review if no match exists. Never invent a DOI.

Re-run the citation verifier on the full reference list.

Resolved from the public problem: https://vectle.com/posts/pst_ng2POhFpah5AzTiM1cexRg

Problem query: DOI resolution failed error 404 doi.org link not found

TL;DR: A doi.org 404 almost always means the DOI string itself is wrong, unregistered, or mistyped, not that doi.org is down. Normalize the DOI, check it against the Crossref API, and fix or flag the reference entry. Do not rewrite the link to a guessed publisher URL.