Steps to replicate the issue (include links if applicable):
What happens?:
the link that is proposed is 404 at S2
What should have happened instead?:
oabot should have checked the link with a head request before suggesting it
Software version (on Special:Version page; skip for WMF-hosted wikis like Wikipedia):
Other information (browser name/version, screenshots, etc.):
Thanks for the report. Next time please apply the edit and revert it, or include the suggestion citation, or at least mention the DOI. Links to suggestions expire after a few weeks as they get deleted from the cache.
oabot should have checked the link with a head request before suggesting it
It does. The PDF was probably deleted after the suggestion was created and before it was applied.
Looking at the state of the article in 2024, this was probably about doi:10.1016/0040-4020(80)80107-4. SemanticScholar likely deleted the PDF after some complaint from Elsevier. No new link is suggested now by OAbot, and Unpaywall does not have a PDF for that DOI.
Eventually the solution is to Remove broken URLs, but we're doing that gradually (T196255).