This seems to be very strange , but this problem appears only when I have a underline character "_" in the URL address.
examplme:

mantis_new.firma - then this problem occured
but after changing it to mantisnew.firma - the problem disappeared ...

I don't understand why it behaves this way but ... maybe this will help some other people who experienced this problem.

I can confirm this problem.
I'm using the CVS Head.
But it's really weird - from the same computer I can login w/ my account, but w/ another account I receive the same message error.
I deleted the other user and re-created, but the problem still exists...

I've just received another phonecall, which described the same behaviour.

One more remark: my problem isn't browser-specific: both IE and Firefox.
But I wasn't able to reproduce it on my own computer, only on the user's desktop PC.

And we don't have underline in the URL, nor in the user's name.
This problem seems to be connected to 0006503.

I just want to confirm that this bug is present for me too... I'm trying to install mantis at my new job and I looked a little bit stupid when i was unable to create an account... Please solve this problem ASAP , or a workaround...!!

Any update?

This problem is easy to reproduce. Simply copy the Mantis files into the webroot, as opposed to the <webroot>/mantis folder. One trick to fix this (if say you want to put Mantis on mantis.mysite.com) is to get a .htaccess to redirect a URL like "mantis.mysite.com" to "mantis.mysite.com/mantis".

One word of advice about Mantis. CVS it yourself, and fix the bugs on your own. Keep track of your fixes, and redo them whenever you upgrade Mantis.

Lots of security bugs and misfeatures. If you ever use it in a corporate setting, the problems start popping up like wild fire. That the file 'proj_doc_page.php' for example. Some problem with Project Docs and public/private setting. Had to fix that ourselves.

I was experiencing the same problems.

I found that a short term work-around appeared to be downgrading the IE security level from medium to low. I am using IE 6.0.2900

About same problem. see 0006774

same issue here but no underline in the name. Works fine with ip address but not name under IE6. Works fine on firefox. Changing the security level makes no difference and there is no P3P issue (the site has a p3p and is valid).

Correction - There is an underscore in the server name, and that is the issue. IE6 will not send cookies to a server with an underscore in the name. This is an IE6 (or patched ie5) issue, not a mantis or PHP issue.

This may be related to an IIS "security feature". See http://groups.google.com/group/microsoft.public.inetserver.iis/browse_thread/thread/c2c90707d33a5f0f/4783319c51be5d29?q=underscore&rnum=6#4783319c51be5d29 .

It appears that certain characters are not allowed in cookies, either in the web site or path.

Same problem after upgrading to 1.2a1 on apache...

same problem in apach2 in 1.2.0rc1 using IE 8.0 but firefox is OK.

Any help?

My problem is resolved after reinstalling latest 1.2.0rc2 2009-07-17-master-1.2.x-918d8e3 version.

Is anyone else experiencing this problem with 1.2.0RC2? I'll close this bug if I don't get any negative response to this question.

Same problem with 1.2.0rc2 using IE.
Firefox works fine.

Is anyone else experiencing this problem with 1.2.12?

I have just tested on 1.2.13dev with IE6 and no problem to login.
No problem, too, with IE8 in quirks mode

Thanks Lapinkiller for testing

This issue is not reproducible with the current version of MantisBT.

We recommend that you upgrade to the latest stable version [1]; if after doing so the problem persists, do not hesitate to reopen the issue, with additional relevant information.

[1] https://sourceforge.net/projects/mantisbt/files/mantis-stable/