Gmail has evolved to be one of the most popular webmail services on the planet, mostly because of its great features like IMAP, POP3, SMTP and Gmail labs, but non the less, because it is associated with Google. With 200 million users that login to their accounts, sometimes multiple times a day, Gmail login problems may be a subject for many users. The following is a list of common login issues that you might experience, and ways to solve them:

Lost password – either if you lost your password, or made too many login attempts to the point that your account is blocked, look for Gmail password recovery page and follow the instructions. You will be asked to enter your secondary email address that you assigned for this purpose.
Cookies are disabled – most of the popular browsers give an option to disable cookies for the user convenience, and cookies that are disabled might lead to login problems because Gmail is using session cookies to allow persisting a connection sparing the need to login every time you open your browser. There for it is essential to keep cookies enabled.
JavaScript is disabled – same as cookies, but this time with JavaScript. Gmail uses JavaScript to create cookies, so it is obvious that if JavaScript is disabled Gmail might fail to login to your account.
Temporary Error (502) – If you’re seeing a ‘Temporary Error (502)’ message when you try to sign in to Gmail, it means that your mail is temporarily unavailable. These errors generally resolve themselves within a few minutes, so please wait a bit before trying to log in again. Please note that while Gmail is inaccessible, your messages and personal information are safe.