How to Resolve Error 999 of Yahoo? A few fails, faults occur while using Yahoo mail or sometimes Ymail stops services and shows error. In the list of errors, a most common error is 999. 999 is a runtime issue which is indeed temporary in nature but can deny your access. This issue is generally caused by several requests to Yahoo which originates from your computer system. In case, you are having these troubles and looking for a perfect solution, then you have come to the right place. As Yahoo Technical Support will cover everything you needed. However, if you required more information about this or have other queries you can also get in touch with us!  Open the Tools in the menu of your web browser by clicking it and then select Internet Options.  Here, in the options, click the Privacy tab to continue further.  Use the slider to mark the security level medium.  Now, click Ok to confirm your actions.  Restart your computer and follow the next steps to do the same settings in Chrome or Mozilla Browser.  Now, in the 3rd party browsers, select Options from the side menu panel and choose Settings.  Here from the Settings, select Content Settings, click the radio button which is next to Allow Local Data.  After that, close the Window and feel free to restart your browser.  If the above steps don’t fix the error, follow the forthcoming guidelines to fix them.  Open the Start menu by clicking it.  In the find bar, type Windows Defender and hit an Enter button on your keyboard.  This action will lead you to Windows’ malware scanner and removal tool.  Run a full scan to get to know the main reason behind the issue. Furthermore, that’s how you can completely scan your computer system.  If this asks for updates then, click the back arrows to get back to the main settings.  Here, click the update button and get the latest updates.  After updating, run a complete scan and once the completion is successful you won’t find any error near to you. If any issue persists, our support team is always geared up to provide the best services and also do not let the users stuck somewhere. Let it be any reason, you’ll be guided with all the necessary information and best possible solutions. Just contact Yahoo Contact Number Ireland @+353766042738 to get the most relevant answers to your problems. The Yahoo Customer Support Ireland includes highly experienced technicians and highly professional engineers, who are just sitting for you and your queries. So do not hesitate to call and talk to them and do not stay in trouble for long as the team is always pleased to serve customers without letting them wait. Source