Hrn. That is an interesting error... Not that it were particularly mysterious ... quite the opposite, I know precisely what that means, even if I don't know why'd you get it, as I myself didn't have the issue on three different computers, several browsers each, or even my cell phone with Firefox/FF Beta/Chrome/native browser (excluding closing the browser and trying to directly access the editing section without going through the login).* I believe you were using Firefox (as I recall you mentioning it one time when you didn't have internet) and some manner of Windows?
 - It means that either your computer decided to eat the session key, or it wasn't, for some reason, set for the page you're looking at (and thusly tried to connect to the database with the default values). Made the login page session start slightly more aggressive and temporarily added some slight debugging text - if you move to any other category from the login successful/failed page, the very upper left corner (above even the header title) should say "Session set active", and on the next line have a quite a few of seemingly random letters and numbers. See whether it says something; if not, then I'll probably add a few more different connections/sessions and hope that one of them will go through (which is a very common practice, to be fair, since people's computers apparently do not like types of connections and manners of storing session info all the time).

(Will probably also add a terminate session link at the footer of the edit page ... if for no other reason, then it would make logging back in more easier.)

*I was logging in with my own account, but that shouldn't make a difference in the session being maintained. If there was an issue with your privileges or password, it would have said something else.

Edit: Do we still have a Nessa amongst us?

(Hrn... I did remember you were quite color-shade-blind, and hence sort of assumed you probably wouldn't be able to fully relate what I was going at with the colors and contrast, but if both the person who is half-colorblind and the person who lives in a world that is often just too colorful and sharply contrasted have issues, then it probably goes to show that the situation with colors and contrast is bad indeed... In my case, though, the medium-light theme (coupled with the lowest brightness setting possible for the screen and the lights in the room turned on) is the least painful. The dark theme's pure white text, especially with the garish neon tags mingled in (which also have white text on them, despite all the brightness) is just too much - my contrast sensitivity simply cannot take it. Makes eyes adjust to the nice dark backround, which means that anything light is quadruple the brightness... I guess I know how Nightwalkers feel?)

Anyway, vote for migrating/not migrating to Iwaku? At the present, I am neutral, since I am sort of willing to see whether whatever Mahz is doing now works. If the situation hasn't improved after two weeks, I'll probably move my vote.

For moving: 3 (Legion, Mercinus, ASTA)
Neutral: 5 (Shien, Nessa(n/s), Ashgan(n/s), Rhae, Veridis)
For staying: 2 (Yoshua(n/s), TNY)
(10/11)