>>1223
Hmm, this error basically means that as it tried to log in, the site did not give a cookie that the login script expected to be given. This suggests the site has changed its login process since that script was written, or maybe an unusual error like your login password was wrong or something or the login page now has a captcha, so the login just failed.

For all complicated login situations, I recommend Hydrus Companion now. It lets you copy your cookies right from your logged-in browser to Hydrus using the Client API:

https://gitgud.io/prkc/hydrus-companion