Sometimes a user cannot vote on an election.
They see the message:
You must log in to vote in this election - please try following the link from your Special:SecurePoll on your local Wikimedia site.
This seems to be intermittent. If the user tries again, they are often successful.
Possibly related log message:
Error
- mwversion: 1.37.0-wmf.18
- reqId: 5cc88050-9480-4e98-911d-e38a7704aa8c
- Find reqId in Logstash
- Find normalized_message in Logstash
Session "{session}": Metadata has an anonymous user, but a non-anon user was provided
From page https://vote.wikimedia.org/wiki/Special:SecurePoll/vote/1101.