Fixing Magento Login Problem after a Fresh Installation

This is just a quick little note to suggest two ways to solve the problem that you cannot log in to your Magento admin interface after a fresh install of Magento.

The Problem

The problem will manifest itself as a redirect back to the login screen, even though you typed the right username and password. If this problem is affecting you, you will be redirected back and see no error message. This indicates you have the right credentials, but the Magento Admin is just not letting you in. You can verify it by typing the wrong username and password, you’ll see you get redirected back and it shows an error message.
The problem occurs because the Magento backend tries to set a cookie on your browser, and then for some reason when you next make a request, the cookie is gone(or was never there). This makes Magento think you have never logged in, and of course it redirects you to the login screen. So the real guts of it is the missing cookie, we need to find out why it’s missing.

There are two solutions I have come across that will solve this, there may be others too, so please feel free to post them below. Both of these solutions have been suggested in the comments of my post on Setting up Apache Virtual Hosting.

Solution 1: Domain Name with no dots

This is the most common solution, if you have set up Magento to run locally (on MAMP for example) then you may be accessing the Apache webserver using the localhost hostname. A security setting in browsers means that the cookie will not be set, though apparently in FF3 at least, this behavior is a bug?.
So simply stop using localhost, you can use your localhost interface (e.g. 127.0.0.1 or 127.0.1.1). To determine your localhost interface you can look at the contents of your hosts file:

# Look for the number to the left of localhost
cat /etc/hosts
or your interface configuration.
# Look for interface loX with the LOOPBACK flag (probably lo0)
ifconfig

Once you know which number to use, you can replace localhost with the number. If you have already installed Magento using localhost then it will keep writing out links to localhost, even after you have changed to using the IP address, you will need to change the base_url values in the core_config_data table, you can run a query like this to find the right config values to change:

SELECT * FROM core_config_data WHERE value LIKE "%localhost%";

This should identfy two config values that will need to update with a query like:

UPDATE core_config_data SET value="http://127.0.0.1/" WHERE path IN ('web/unsecure/base_url','web/secure/base_url') ;

I’m going to assume you know to put the right value into that query, and not use the example one I have provided!

After changing that value you should delete your var/cache contents, and then refresh the page. Now you should have Magento running on an IP address, not a hostname with no dots in it. Of course you could always set up a fake domain name like www.testing.com by using a Virtual Hosting setup like I describe in my post on how to configure a MAMP Virtual host.

Solution 2: Timezone differences between server and client
One other, less likely problem, is that the cookie is being set, but expiring immediately. To check this you can inspect the cookies your browser is holding, and check if there is one there from Magento. If there is then check both the timezone your magento installation is using , and the one you have set locally, perhaps your local time is not set properly?

Hopefully one of these two solutions will get you back on track and able to log in to your newly installed Magento. Feel free to post problems or suggest other solutons in the comments below. I’m always more than happy to update my posts with helpful tips from readers.