Hi kevin,

Answer me plasase, My system use load balancing on five server, but some time there are this errors:

System.InvalidOperationException: Collection was modified; enumeration operation may not execute. at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource) at System.Collections.Generic.Dictionary2.Enumerator.MoveNext() at System.Linq.Enumerable.WhereEnumerableIterator1.MoveNext() at System.Collections.Generic.List1..ctor(IEnumerable1 collection) at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source) at Umbraco.Examine.UmbracoExamineIndex.OnDocumentWriting(DocumentWritingEventArgs docArgs) in D:\a\1\s\src\Umbraco.Examine\UmbracoExamineIndex.cs:line 142 at Examine.LuceneEngine.Providers.LuceneIndex.AddDocument(Document doc, ValueSet valueSet, IndexWriter writer) in D:\a\1\s\src\Examine\LuceneEngine\Providers\LuceneIndex.cs:line 794 at Examine.LuceneEngine.Providers.LuceneIndex.ProcessIndexQueueItem(IndexOperation op, IndexWriter writer) in D:\a\1\s\src\Examine\LuceneEngine\Providers\LuceneIndex.cs:line 1334 at Examine.LuceneEngine.Providers.LuceneIndex.ProcessQueueItem(IndexOperation item, IndexWriter writer) in D:\a\1\s\src\Examine\LuceneEngine\Providers\LuceneIndex.cs:line 1133 at Examine.LuceneEngine.Providers.LuceneIndex.ForceProcessQueueItems(Boolean block) in D:\a\1\s\src\Examine\LuceneEngine\Providers\LuceneIndex.cs:line 981