Fixing Failing DNN Scheduler 7.3.x Issues

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.

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.

DELETE FROM WebServers
WHERE ServerName = 'PROD_WEB'
    AND Enabled = 0

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