If you are, confronting AOL error code 400 in your system while opening a new website then there can be various reasons why the server has declined your request. However, once you implement the below-mentioned steps, then you can solve the problem quickly: Run the antivirus software for removing the viruses and malware. Remove the entire junk files from your system. Repair Windows registry entries related to error 400 of AOL. Uninstall and then install AOL Messenger. For repairing the missing and corrupted file, run Windows SFC. Install the available updates on your system. Clean installation of Windows may also resolve the issue. Even after executing these steps if you still confront Http status error 400 then you need to call AOL customer service number where you can speak with experts. The customer team will give you proper guidance that is required for removing the issue altogether.