Problem:

I had a new installation of magento. But I was unable to login as an administrator. I went

to the admin login page, entered correct username and password but was redirected to the

same login page. I could not enter the dashboard page. Error message is displayed when I

enter wrong username or password. But nothing is displayed and I am redirected to the same

login page when I insert correct username and password.

Solution:

I googled and found these solutions:-

1) Use 127.0.0.1 instead of localhost in your url, i.e. using

http://127.0.0.1/magento/index.php/admin instead of
http://localhost/magento/index.php/admin . But this didn’t solve my problem.

2) Since I am using Windows XP, I was suggested to open “host” file from
C:\WINDOWS\system32\drivers\etc and have 127.0.0.1 point to something like magento.localhost

or even 127.0.0.1 point to http://www.localhost.com . But this also didn’t work either.

3) This solution finally helped me out of this problem. The solution was to modify the core

Magento code. Open

app/code/core/Mage/Core/Model/Session/Abstract/Varien.php. Comment out the

lines 80 to 83. The line number may vary according to the Magento version. But these lines

are present somewhere near line 80. You have to comment the comma (,) in line: $this-

>getCookie()->getPath()//,

// set session cookie params
session_set_cookie_params(
$this->getCookie()->getLifetime(),
$this->getCookie()->getPath()//,
//$this->getCookie()->getDomain(),
//$this->getCookie()->isSecure(),
//$this->getCookie()->getHttponly()
);

Well, I am out of this problem. Hope, this solution you also help you.

Update (For Magento 1.4.*)

In Magento 1.4, you have to comment code from line 86 to 98 in

app/code/core/Mage/Core/Model/Session/Abstract/Varien.php. Like this:-

/*  if (!$cookieParams['httponly']) {
	unset($cookieParams['httponly']);
	if (!$cookieParams['secure']) {
		unset($cookieParams['secure']);
		if (!$cookieParams['domain']) {
			unset($cookieParams['domain']);
		}
	}
} 

if (isset($cookieParams['domain'])) {
	$cookieParams['domain'] = $cookie->getDomain();
} */