Core

Did you experience any JavaScript errors on that behaviour?

No, there are no JavaScript errors

I'm still redirected to an error page after the login

I don't know if this is connected, but I have session timeout problems in IE8 (IE7 too). For me it works perfectly for a while, and then suddenly I'm logged out by a session timeout.

Sometimes it seems like it is happening when I open up tabs and visit other websites while being logged in to TYPO3.

In addition I have trouble being logged in on the frontend of my websites. One is running on 4.1.12 and the other is 4.2.8, I think it happened around 4.1.10 and 4.2.6. I didn't report it then because I hoped it would be fixed in newer versions, so I simply resorted to other browsers.

I'll try and be careful observing when the session timeout happens.

Take a look to #19883 for further possible solutions.

I have just encounter the same issue. I was using 4.2.6 and upgraded to 4.2.8, but that did not help. It turns out that I was running this site in IE8's new "Compatibility mode", and when I switched it back to NOT running in this mode it works perfectly again.
I have not looked into what this compatibility mode actually does, but apperently it interferes in a bad way.
Hope that this will bring us closer to sorting that issue (and that this is related to the bug that you have experienced).
NB: You can administer your compatibility mode if you open "Functions"=>"settings for compatibility views" (translated from a danish version).

By the way as Oliver asked for JS errors I seem to get a few (none of them seem to be able to cause the bug I think). Anyway here they are:
This is printed from Microsofts IE debugger:

Et objekt er obligatorisk prototype.js, linje 3788 tegn 7
'x' er null eller ikke et objekt prototype.js, linje 3827 tegn 7
Et objekt er obligatorisk prototype.js, linje 3788 tegn 7
'Event.pointer(...).x' er null eller ikke et objekt prototype.js, linje 3796 tegn 33
Et objekt er obligatorisk prototype.js, linje 3788 tegn 7
'Event.pointer(...).y' er null eller ikke et objekt prototype.js, linje 3797 tegn 33

Problem occurs here as well with IE8 and "Compatibility View" activated (reproduced in 4.2.8 and early 4.3 version due to customer complaints; have neither checked with current trunk nor other IEs). Version of IE8: 8.0.6001.18702

To reproduce this error (haven't examined the reason yet):
- Activate "Compatibility View" in IE8
- Log in to backend
- Switch to frontend view and navigate there while being logged in to TYPO3.
- Try to use the backend => you're session is lost

I can lose the session in IE8 (TYPO3 4.1.12) without having compatibility view activated.

I open the browser, login to the backend, open a new tab, go to the front end and navigate a little, and bingo, session is lost.

So I don't think it's totally related to compatibility view.

I can't confirm losing BE session without Compatibility View.

Although and after playing around a bit, it seems (not to sure here) to be depending on the state of the Admin Panel and the shown fe editing options, so there might be situations different to the ones I'm testing with.

At least it should be possible to reproduce the error now which should allow to eventually track it down...

The following works for me (fixes the problem of losing session while navigating through the frontend):

TS setup:
config.headerComment (
-->
<meta http-equiv="X-UA-Compatible" content="IE=8" />
<!--
)

Ralf, I just tried out your solution, but with no luck.

I inserted the code in the frontend, confirmed that it showed up in "View source". While being on a front-end page, I opened up a new tab, logged in to the backend, switched to the front-end page, navigated to another page and then the session in the frontend was lost.

Have a look at #21511 - could be the reason for lots of IE8 problems

I did not have this error after #21065 was committed.

Does this still happen to someone with 4.2.11 and 4.3.1 or newer?

Michael, is this problem fixed?