When you configure the Windows Server Failover Cluster Quorum, using “Node and File Share Majority” (typically in a even count Node Cluster), a error can arise referring to <not a valid file share path>.

Investigating that you have set the proper permissions for the Share and Folder on the Server hosting the Share. With the least privileges you must set the following rights:
e.g. (Virtual Cluster Name is Cluster01 so the Cluster Virtual Network name its Cluster01$, Directory on the File Share host is W:\ClusterQuorumFS$ [hidden Share]).

  • Share Level Permissions: Cluster Virtual Network name with FULL rights     
    Command line Statement:
    net share ClusterQuorumFS$=W:\ClusterQuorumFS$ /GRANT:Cluster01$,FULL
  • Folder Level Permissions: local Administrator, Cluster Virtual Network name + any subsequent Cluster Virtual Network names of additional Cluster’s with FULL rights
    Reminder: every Cluster will create it’s own Subfolder under the Shared Directory if the same Share is used for all Cluster’s in the Environment.    
    Command line Statement:
    cacls W:\ClusterQuorumFS$ /G BUILTIN\Administrators:F Cluster01$:F

If the Share is ready but you cannot successful configure the Quorum in the Failover Cluster Manager using the Configure Cluster Quorum Wizard, try to use the following command line Statements (cluster.exe):

    1. Create a new Cluster Resource of Type File Share Witness (FSW) in the Cluster Group
      Cluster.exe /cluster:Cluster01 res "File Share Witness" /create /group:"Cluster Group" /type:"File Share Witness" /priv SharePath=\\FS01\ClusterQuorumFS$
    2. Bring the new Cluster Resource online
      Cluster.exe res "File Share Witness" /online
    3. Set Cluster to File Share Witness as Quorum
      Cluster.exe Cluster01 /quorum:"File Share Witness"
    4. Set Retry Period on FSW Timeouts to 15 minutes instead of 1h (default)
      Cluster.exe Cluster01 res "File Share Witness" /prop RetryPeriodOnFailure=900000:dword

    The above Statements are working only with Cluster.exe. If the Nodes are running on Windows 2012, then you have to use the corresponding PowerShell cmdlets.
    See at <http://technet.microsoft.com/en-us/library/jj573624.aspx>