After I type in my PWD & click on blue "Log in" button, it displays (red-stop-sign) "There seems to be a problem with your login session; this action has been cancelled as a precaution against session hijacking. Please resubmit the form." JoeNMLC (talk) 03:14, 7 November 2023 (UTC)
OK. I was getting the same, both at commons and at meta, earlier today. (I'd logged out the other day to test a problem with a fresh account.) Usually when this happens, just trying to login again works; today, it just kept giving me the problem-with-your-session box.
What finally worked was to delete my cookies for meta.wikimedia.org and commons.wikimedia.org and try logging in again. —Cryptic 03:15, 7 November 2023 (UTC)
Could be related to yesterday's deployment of https://gerrit.wikimedia.org/r/c/operations/mediawiki-config/+/966798 rOMWCbeb76abd7344: Generalize Meta/Commons exceptions for CentralAuth cookie handling?
There errors don't seem to be monitored on https://grafana.wikimedia.org/d/000000004/authentication-metrics.