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Fixing Failing DNN Scheduler 7.3.x Issues

Posted on Sep 23, 2015

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In the past few months, I have had to work with various issues with DNN/Evoq sites not executing scheduler jobs.  A number of various blog posts, as well as forum posts, have been started on the issue, and all point to a similar issue with regards to case-sensitivity with the scheduler and the web server name.  I had a recent situation though where I had fixed all of the issues outlined but was still seeing an error.

The Error

There was a single, non-descript error in the EventLog when the scheduler went to start.  The error detail was as follows.

System.InvalidOperationException: Sequence contains more than one matching element at System.Linq.Enumerable.Single[TSource](IEnumerable`1 source, Func`2 predicate) at DotNetNuke.Services.Scheduling.Scheduler.CoreScheduler.GetServer(String executingServer) at DotNetNuke.Services.Scheduling.Scheduler.CoreScheduler.LoadQueueFromTimer() at DotNetNuke.Services.Scheduling.Scheduler.CoreScheduler.Start()

The error message although cryptic to site administrators makes it easy to fix.

The Fix

Based on the above error I assumed that I had multiple entries with the same web-server name. So I ran the following query to check on this.

SELECT ServerId, ServerName, Enabled
FROM Webservers

The results of this query looked similar to the following.

ServerId ServerName Enabled
2 Test-Server false
3 PROD_WEB false
4 PROD_WEB false
5 PROD_WEB true

The problem was with the duplicate entries for the PROD_WEB server, not a case sensitivity issue, but a true data issue. The fix was simple.

WHERE ServerName = 'PROD_WEB'
    AND Enabled = 0

I hope that this helps those of you with scheduler issues!