How to Fix Yahoo Runtime Error 999

By Jane Buchanan

When trying to access one of Yahoo's many services, you may sometimes instead reach an "Error 999" page. While such an error is usually temporary, it can also be caused by a large number of requests to Yahoo originating from your computer. In such a case, to protect its servers from automated queries, Yahoo can deny you access, presenting you with an "Error 999" page instead. Fortunately, it is possible to regain access to Yahoo by editing your browser's settings and ensuring that no unauthorized program is sending automated queries from your computer.

Enable Cookies in Your Browser

Step 1

Open the "Tools" menu in Internet Explorer, if you are using that browser to access Yahoo, and select "Internet Options." Click on the "Privacy" tab and use the slider to set your browser's security level to Medium. Select "OK" to confirm your new settings. Close Internet Explorer and relaunch it.

Step 2

Open the "Firefox" menu in Mozilla Firefox and select "Options." Click on the "Privacy" tab and, from the History drop-down menu, select "Remember history." Click on "OK" and restart your browser.

Step 3

Click on the "Tools" icon in Google Chrome to open the Tools menu and select "Settings." Click on the "Show advanced settings" shortcut and select "Content settings." Click on the radio button next to "Allow local data to be set" and close the window. Restart Google Chrome.

Check for Malware and Unauthorized Users

Step 1

Open the Windows Start screen, type "Windows Defender" and press the Enter key to launch Windows' built-in malware scanner and removal tool. Run a full scan of your computer to ensure that no malicious applications are currently installed. Such programs can send automated requests to websites such as Yahoo.

Step 2

Check whether your Wi-Fi connection is password-protected. To do so, log in to your router's administration interface and check if a password has been set. If you experience difficulties while doing so, refer to your router's setup manual. If no password has been set, create one and confirm your new settings. To be able to connect to your router, your computer will of course need to use the same password. You can set that password on your computer by opening the Start screen and typing "network." Select "Network and Sharing Center" and click on "Change adapter settings." Right-click on your wireless connection's icon and select "Status." Click on "Wireless Properties," enter your password and click on "OK" to confirm it.

Step 3

Enable your Windows Firewall. To do so, open the Start screen and type "firewall." Click on "Windows Firewall" and select "Turn Windows Firewall on or off." Click on "Turn on Windows Firewall" under both private and public network settings. Select "OK" to confirm your new settings.

Tips & Warnings

  • If you are still unable to access Yahoo, try connecting to that website using a different browser, computer or Internet connection.