Full Sync Error: "[System.InvalidOperationException] Collection was modified; enumeration operation may not execute" (210579)

A full sync fails with the following error message:

"[854003] Processing task FullSync failed.

    [System.InvalidOperationException] Collection was modified; enumeration operation may not execute.

       at StdioProcessor.StdioProcessor._Execute(Job job)

       at VI.JobService.JobComponents.ADSComponent.Activate(String Task)

       ---- Start of Inner Exception ----

       at VI.JobService.JobComponents.ADSComponent.Activate(String Task)

       at VI.JobService.JobComponents.ADSComponent.FULLSYNC()

       at VI.JobService.JobComponents.ADSComponent._DoFullsync()

       at VI.JobService.JobComponents.NsJobComponent.ResetFullsyncSemaphore(IConnection Connection, String SemaTable, String WhereClause, String SemaColumn)

       at VI.JobService.JobComponents.viSyncErrLogger.FlushMessages()

       at System.Collections.Generic.List`1.Enumerator.MoveNext()

       at System.Collections.Generic.List`1.Enumerator.MoveNextRare()

       at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)"

Multi-threading was earlier introduced for the ADS-Sync in order to improve performance. This could be influenced with the job parameter "SingleThread" which comes from the Configuration Parameter TargetSystem\ADS\SingleThread in the standard process.

Prior to version 6.1.3 it was discovered that the AD-Interface is not able to multi-thread under all circumstances. So with 6.1.3 multi-threading for the sync was removed.

Activate the Configuration Parameter TargetSystem\ADS\SingleThread:

In Designer:

- Getting Started | Edit configuration parameters

- Select Edit configuration parameters under Tasks

- Expand TargetSystem | ADS, enable SingleThread and commit the change to database.  No compile is necessary.