Understanding the Access Denied Error Message when Mapping a Network Drive to SharePoint Online

  by Brian Petersen, MSFT SharePoint Online provides users the ability to map a network drive to a document library allowing a user to navigate to and open files directly from Windows Explorer. This blog is intended to direct users to a Knowledge Base article that’s been published to help not only setup and configure mapped network drives, but also address common issues and steps to resolve.  In the More Information section of this blog you’ll see a link to the KB Article, but you’ll also see more details around the most common scenario we see in support.  Note This blog and the KB article do not apply to Microsoft Office 365 for professionals and small businesses.   More information: The Knowledge Base article entitled “How to configure and to troubleshoot mapped network drives that connect to SharePoint Online sites in Office 365 for enterprises” can be found here: KB2616712 . Ensure all the steps are completed in the KB, but also note the comment about the cookie expiring in the first set of solution steps. The comment in the KB states “Be aware that the cookie will eventually time out”. Certainly, having the WebClient started in your client machine’s Services, along with adding your SharePoint site to the Trusted Sites Zone of your Internet Explorer browser, are both important solutions to Mapped Drive issues. However, you will continue to encounter an Access Denied error periodically – mainly after rebooting the computer or when you haven’t logged in (authenticated) to SharePoint Online over an extended period of time, generally 8 hours., One common scenario is when a user locks the computer at the end of the workday, returns the next day, and logs in to their work computer. If that worker tries to access the mapped drive he or she will get the following error. Path is not accessible. You might not have permission to use this network resource. Contact the administrator of this server to find out if you have access permissions. Access Denied. Before opening files in this location, you must first add the web site to your trusted site list, browse to the web site, and select the option to login automatically' The user receives this error because the session cookie  for SharePoint Online has expired and must be “refreshed” in order to successfully access the mapped network drive again.            

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Understanding the Access Denied Error Message when Mapping a Network Drive to SharePoint Online