Content Deployment Failed Error

You started with content deployment , defined the content path and job . Everything looks good till you actually run the job and bang the mighty long error

"Failed to compare two elements in the array. at System.Collections.Generic.ArraySortHelper`1.QuickSort[TValue](T[] keys, TValue[] values, Int32 left, Int32 right, IComparer`1 comparer) at System.Collections.Generic.ArraySortHelper`1.QuickSort[TValue](T[] keys, TValue[] values, Int32 left, Int32 right, IComparer`1 comparer) at System.Collections.Generic.ArraySortHelper`1.Sort[TValue](T[] keys, TValue[] values, Int32 index, Int32 length, IComparer`1 comparer) at System.Collections.Generic.ArraySortHelper`1.Sort(T[] items, Int32 index, Int32 length, IComparer`1 comparer) at System.Array.Sort[T](T[] array, Int32 index, Int32 length, IComparer`1 comparer) at System.Collections.Generic.List`1.Sort(Int32 index, Int32 count, IComparer`1 comparer) at System.Collections.Generic.List`1.Sort(IComparer`1 comparer) at Microsoft.SharePoint.Deployment.WebSerializer.GetDataFromObjectModel(Object obj, SerializationInfo info, StreamingContext context) at Microsoft.SharePoint.Deployment.DeploymentSerializationSurrogate.GetObjectData(Object obj, SerializationInfo info, StreamingContext context) at Microsoft.SharePoint.Deployment.XmlFormatter.SerializeObject(Object obj, ISerializationSurrogate surrogate, String elementName, Boolean bNeedEnvelope) at Microsoft.SharePoint.Deployment.XmlFormatter.Serialize(Stream serializationStream, Object topLevelObject) at Microsoft.SharePoint.Deployment.ObjectSerializer.Serialize(DeploymentObject deployObject, Stream serializationStream) at Microsoft.SharePoint.Deployment.SPExport.SerializeObjects() at Microsoft.SharePoint.Deployment.SPExport.Run() *** Inner exception: Object reference not set to an instance of an object. at Microsoft.SharePoint.SPFeature.EnsureProperties() at Microsoft.SharePoint.SPFeature.get_TimeActivated() at Microsoft.SharePoint.Deployment.WebSerializer.ExportFeatureComparer.System.Collections.Generic.IComparer.Compare(ExportObject exportObject1, ExportObject exportObject2) at System.Collections.Generic.ArraySortHelper`1.QuickSort[TValue](T[] keys, TValue[] values, Int32 left, Int32 right, IComparer`1 comparer)"

OR

" Content deployment failed.The exception thrown was 'System.InvalidOperationException' : 'Failed to compare two elements in the array.'

Solution :
The exception basically means that some of the features activated at the site collection level no longer exist on disk. Their feature definition files have probably been deleted. This can easily occur if you delete some features from your solution packs without deactivating/reactivating all features on deployment .

So pin point the features causing trouble and remove it and you will be good to go .