Today none of the articles I tried to enter with PMID could be found, DOI works fine, but this one is so old that it only has PMID and no DOI associated.
Using this PMID: 29377013 I see this error in the debug: Error: No Pubmed Data found - Most likely eutils is temporarily down
Edit: From eutils webpage:
Maintenance in progress The page you are trying to reach is currently unavailable due to planned maintenance. Most services will be unavailable for 24+ hours starting 9 PM EDT on Friday, July 25, 2025.
Just as an update, PubMed's metadata service is still returning an internal server error, albeit a different one:
Your request could not be processed due to a problem on our Web server.
Unless they've announced API changes that we haven't seen, I'd guess that they're still working on things. If it's still not working tomorrow, we'll contact them.
I see this error in the debug:
Error: No Pubmed Data found - Most likely eutils is temporarily down
Edit: From eutils webpage: