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Case 2 - "Internal Server Error" message after Host Login

Case 2 -

DNN Version: 07.00.06 - Community Edition

Symptoms

  1. Whenever admin or super user tried to login to the site, it would show the error message:
    Internal Server Error The server encountered an internal error or misconfiguration and was unable to complete your request. Please contact the server administrator to inform of the time the error occurred and of anything you might have done that may have caused the error. More information about this error may be available in the server error log.
  2. So the backend was not available at all, but the front end was working fine.

Troubleshooting

  1. We weren't very hopeful to find any useful information from the EventLog table but we decided to give it a try.
  2. The first challenge was that this site was hosted on a shared hosting plan. So we had no direct access to SQL Management Studio to run queries again the database. And of course the backend was not available, so we couldn't go to Host/SQL. So how to query the database then? Simple, we have an app for that!
  3. By installing this simple application, which I will be calling SQL App, we were able to run queries from the site at /SQL.aspx (remember in the end to remove SQL App from the site, or you will be exposing your database to everyone!)
  4. We run the following query to give us the last 10 entries from the EventLog table in the hopes that one of the log entries could provide us with some clues:
     SELECT top(10)* FROM EventLog WHERE LogTypeKey like '%EXCEPTION%' ORDER BY LogCreateDate DESC
  5. We found very recent exceptions on the log and one of those caught our attention:
     Message DotNetNuke.Services.Exceptions.PageLoadException: Object reference not set to an instance of an object. ---> System.NullReferenceException: Object reference not set to an instance of an object. at DotNetNuke.Entities.Portals.PortalSettings.GetPortalSettings(Int32 tabID, PortalInfo portal) at DotNetNuke.Entities.Portals.PortalSettings..ctor(PortalInfo portal) at DotNetNuke.Entities.Tabs.TabController.IsSpecialTab(Int32 tabId, Int32 portalId) at DotNetNuke.Web.UI.WebControls.DnnRibbonBarTool.EnableTool() at DotNetNuke.Web.UI.WebControls.DnnRibbonBarTool.ProcessTool() at DotNetNuke.Web.UI.WebControls.DnnRibbonBarTool.OnPreRender(EventArgs e) at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) --- End of inner exception stack trace ---
  6. It was showing a problem with the DnnRibbonBarTool - But that no longer is the default Control Panel that was shipped with DNN 7.0.6 – The new control panel was called ControlBar.

Solution

  1. First we always do a site files and database backup.
  2. So, as we now had access to the database, we decided to give it a try on switching the Control Panel back to what it was supposed to be the default Control Panel. To do that we run the following SQL statement on the /SQL.aspx interface:
     UPDATE HostSettings SET SettingValue = 'Admin/ControlPanel/ControlBar.ascx' WHERE SettingName = 'ControlPanel'
  3. After this change was done, we forced an application pool recycle by making a small SPACE change to the web.config. This would force the new changes to take full effect.
  4. We tried to log back in the site as super user and voila! The back end was working again!
  5. Remember to remove the SQL App files before you go.

The problem was caused by the old control panel called RibbonBar, which seems to be incompatible with this particular version of DNN.

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