Magento Cookie Issue. Why does it happen?

Question

I have a Magento website up and running. Suddenly I could not Login to the website and could not add products to the website. On login, it simply redirected back to login page from admin end. And on adding product to cart it kept asking for enabling cookies.

Now I have updated the value of "web/cookie/cookie_domain" in core_config_data to "", and it started working fine, though previously the value was the domain name. Can anyone really suggest/explain why does it behave like this?

Answer 1

Magento also has an issue where if you use the bare domain and a subdomain to try accessing the site, it can set two cookies, one for example.com and one for subdomain.example.com.

You will have issues logging in for either front or admin sessions until you delete all the Magento cookies pertaining to your domain. Setting cookie paths, domains and redirecting all bare domain traffic to www or all www traffic to bare domain is necessary to prevent the issue.

Answer 2

search the web and found solutions. Disable redirect to enable-cookies CMS page

 Go to System –> Configuration –> General –> Web –> Browser Capabilities Detection –> Redirect to CMS-page if cookies are disabled = No

for more info you See this link.I hope solve your problem.