"Failed to rebuild documentation" error

[kapitanov]

[11:08:48 Error] ITGlobal.MarkDocs.MarkDocService -> Failed to rebuild documentation [null]
System.InvalidOperationException: Collection was modified; enumeration operation may not execute.
   at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
   at System.Collections.Generic.Dictionary`2.ValueCollection.Enumerator.MoveNext()
   at ITGlobal.MarkDocs.Content.Documentation.Compile(ICacheUpdateOperation operation)
   at ITGlobal.MarkDocs.MarkDocService.Recompile(String id)