I am managing a wordpress site. Recently, I have trouble with the login system. Even though I give the right username and password, it give me the login page again and again, instead of redirect me to the dashboard.
The solution that I usually do is dropping all the tables in the database and import them again. It temporary fixes the problem. But the problem still have possibility to exist.
Anybody know what the problem exactly is?
WordPress login issue, when you have 100% correct username and password, and it does not give you username/password incorrect error, but it just takes you back to login form... it is mostly due to some security measure by some plugin or theme. Most probably a plugin, could by JetPack's security feature, or any other security plugin like Bulletproof Security Plugin & AIO Security (as was the case in OP's situation.)
To make sure if that is the plugin, or which plugin, I suggest a quick work around, ftp/ssh to your server and rename plugins folder as plugins-old, and create new blank folder plugins for now.. and try to login now... this time if you can login perfectly, then it is some plugin, most probably security related plugin, now you can go back to ftp and restore the plugins folder, and then you will have to activate/disable one by one to see which plugin might be the issue.
I have faced this issue many times in the past and above approach has always helped me get it fixed.