Error 5161: Site 2 has no root application defined, so the site will be ignored.

Problem

You see the following error appear irregularly in the SharePoint 2010 server Application log:

Log Name:      System
Source:        Microsoft-Windows-WAS
Date:          [date/time]
Event ID:      5161
Task Category: None
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      [SharePoint 2010 server host machine name]
Description:
Site 2 has no root application defined, so the site will be ignored.
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="Microsoft-Windows-WAS" Guid="{524B5D04-133C-4A62-8362-64E8EDB9CE40}" EventSourceName="WAS" />
    <EventID Qualifiers="49152">5161</EventID>
    <Version>0</Version>
    <Level>2</Level>
    <Task>0</Task>
    <Opcode>0</Opcode>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="..." />
    <EventRecordID>9077</EventRecordID>
    <Correlation />
    <Execution ProcessID="0" ThreadID="0" />
    <Channel>System</Channel>
    <Computer>[SharePoint 2010 server host machine name]</Computer>
    <Security />
  </System>
  <EventData>
    <Data Name="SiteID">2</Data>
    <Binary>0D000780</Binary>
  </EventData>
</Event>

Discussion

The SharePoint Server 2010 installation creates an additional site, SITE_2.  This site can be seen in IIS Manager.  It will create further such sites on removing SharePoint 2010 and subsequently installing it again without removing the SITE_2 website. Thus, you may see a SITE_2, SITE_3, etc.

Solution

These sites can be safely removed using IIS Manager.  Restart IIS after removing these sites.

References

• Event ID 5161 — IIS Web Site Availability
• Site 2 has no root application defined, so the site will be ignored. ????
• IIS SITE_2 and SharePoint 2010

Notes

• This site seems to be a placeholder for prospective web services deployment.  You can see this by reviewing the ApplicationHosts.Config file at C:\Windows\System32\inetsrv\config.  Scroll down to the <Sites> node to see the Site 2 entry.