i am constantly getting this error when i try to create a revision

System.NullReferenceException: Object reference not set to an instance of an object. 
at Umbraco.Courier.Core.Storage.RevisionStorage.(String folderName, String path, Revision& revision) 
at Umbraco.Courier.Core.Storage.RevisionStorage.GetFromDirectory(String name, String directory) 
at Umbraco.Courier.UI.Pages.ViewRevisionDetails.Page_Load(Object sender, EventArgs e) 
at System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) 
at System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) 
at System.Web.UI.Control.OnLoad(EventArgs e) 
at umbraco.BasePages.BasePage.OnLoad(EventArgs e) 
at Umbraco.Courier.UI.Pages.CourierBasePage.OnLoad(EventArgs e) 
at Umbraco.Courier.UI.Pages.CourierBaseLicensedPage.OnLoad(EventArgs e) 
at System.Web.UI.Control.LoadRecursive() 
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

 

when i click on the revision agin to display it i get this

 

System.AggregateException: One or more errors occurred. ---> System.IndexOutOfRangeException: Index was outside the bounds of the array. 
at System.Collections.Generic.List`1.Add(T item) 
at Umbraco.Courier.Core.Storage.RevisionStorage...(FileInfo fi) 
at System.Threading.Tasks.Parallel.<>c__DisplayClass21`2.b__17(Int32 i) 
at System.Threading.Tasks.Parallel.<>c__DisplayClassf`1.b__c() 
at System.Threading.Tasks.Task.InnerInvoke() 
at System.Threading.Tasks.Task.InnerInvokeWithArg(Task childTask) 
at System.Threading.Tasks.Task.<>c__DisplayClass7.b__6(Object ) 
--- End of inner exception stack trace --- 
at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions) 
at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken) 
at System.Threading.Tasks.Parallel.ForWorker[TLocal](Int32 fromInclusive, Int32 toExclusive, ParallelOptions parallelOptions, Action`1 body, Action`2 bodyWithState, Func`4 bodyWithLocal, Func`1 localInit, Action`1 localFinally) 
at System.Threading.Tasks.Parallel.ForEachWorker[TSource,TLocal](TSource[] array, ParallelOptions parallelOptions, Action`1 body, Action`2 bodyWithState, Action`3 bodyWithStateAndIndex, Func`4 bodyWithStateAndLocal, Func`5 bodyWithEverything, Func`1 localInit, Action`1 localFinally) 
at System.Threading.Tasks.Parallel.ForEachWorker[TSource,TLocal](IEnumerable`1 source, ParallelOptions parallelOptions, Action`1 body, Action`2 bodyWithState, Action`3 bodyWithStateAndIndex, Func`4 bodyWithStateAndLocal, Func`5 bodyWithEverything, Func`1 localInit, Action`1 localFinally) 
at System.Threading.Tasks.Parallel.ForEach[TSource](IEnumerable`1 source, Action`1 body) 
at Umbraco.Courier.Core.Storage.RevisionStorage.(String folderName, String path, Revision& revision) 
at Umbraco.Courier.Core.Storage.RevisionStorage.GetFromDirectory(String name, String directory) 
at Umbraco.Courier.UI.Pages.ViewRevisionDetails.Page_Load(Object sender, EventArgs e) 
at System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) 
at System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) 
at System.Web.UI.Control.OnLoad(EventArgs e) 
at umbraco.BasePages.BasePage.OnLoad(EventArgs e) 
at Umbraco.Courier.UI.Pages.CourierBasePage.OnLoad(EventArgs e) 
at Umbraco.Courier.UI.Pages.CourierBaseLicensedPage.OnLoad(EventArgs e) 
at System.Web.UI.Control.LoadRecursive() 
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) 
---> (Inner Exception #0) System.IndexOutOfRangeException: Index was outside the bounds of the array. 
at System.Collections.Generic.List`1.Add(T item) 
at Umbraco.Courier.Core.Storage.RevisionStorage...(FileInfo fi) 
at System.Threading.Tasks.Parallel.<>c__DisplayClass21`2.b__17(Int32 i) 
at System.Threading.Tasks.Parallel.<>c__DisplayClassf`1.b__c() 
at System.Threading.Tasks.Task.InnerInvoke() 
at System.Threading.Tasks.Task.InnerInvokeWithArg(Task childTask) 
at System.Threading.Tasks.Task.<>c__DisplayClass7.b__6(Object )<--- 

---> (Inner Exception #1) System.IndexOutOfRangeException: Index was outside the bounds of the array. 
at System.Collections.Generic.List`1.Add(T item) 
at Umbraco.Courier.Core.Storage.RevisionStorage...(FileInfo fi) 
at System.Threading.Tasks.Parallel.<>c__DisplayClass21`2.b__17(Int32 i) 
at System.Threading.Tasks.Parallel.<>c__DisplayClassf`1.b__c() 
at System.Threading.Tasks.Task.InnerInvoke() 
at System.Threading.Tasks.Task.InnerInvokeWithArg(Task childTask) 
at System.Threading.Tasks.Task.<>c__DisplayClass7.b__6(Object )<--- 

---> (Inner Exception #2) System.IndexOutOfRangeException: Index was outside the bounds of the array. 
at System.Collections.Generic.List`1.Add(T item) 
at Umbraco.Courier.Core.Storage.RevisionStorage...(FileInfo fi) 
at System.Threading.Tasks.Parallel.<>c__DisplayClass21`2.b__17(Int32 i) 
at System.Threading.Tasks.Parallel.<>c__DisplayClassf`1.b__c() 
at System.Threading.Tasks.Task.InnerInvoke() 
at System.Threading.Tasks.Task.InnerInvokeWithArg(Task childTask) 
at System.Threading.Tasks.Task.<>c__DisplayClass7.b__6(Object )<--- 

---> (Inner Exception #3) System.IndexOutOfRangeException: Index was outside the bounds of the array. 
at System.Collections.Generic.List`1.Add(T item) 
at Umbraco.Courier.Core.Storage.RevisionStorage...(FileInfo fi) 
at System.Threading.Tasks.Parallel.<>c__DisplayClass21`2.b__17(Int32 i) 
at System.Threading.Tasks.Parallel.<>c__DisplayClassf`1.b__c() 
at System.Threading.Tasks.Task.InnerInvoke() 
at System.Threading.Tasks.Task.InnerInvokeWithArg(Task childTask) 
at System.Threading.Tasks.Task.<>c__DisplayClass7.b__6(Object )<--- 

---> (Inner Exception #4) System.IndexOutOfRangeException: Index was outside the bounds of the array. 
at System.Collections.Generic.List`1.Add(T item) 
at Umbraco.Courier.Core.Storage.RevisionStorage...(FileInfo fi) 
at System.Threading.Tasks.Parallel.<>c__DisplayClass21`2.b__17(Int32 i) 
at System.Threading.Tasks.Parallel.<>c__DisplayClassf`1.b__c() 
at System.Threading.Tasks.Task.InnerInvoke() 
at System.Threading.Tasks.Task.InnerInvokeWithArg(Task childTask) 
at System.Threading.Tasks.Task.<>c__DisplayClass7.b__6(Object )<--- 

Index was outside the bounds of the array.

System.IndexOutOfRangeException: Index was outside the bounds of the array. 
at System.Collections.Generic.List`1.Add(T item) 
at Umbraco.Courier.Core.Storage.RevisionStorage...(FileInfo fi) 
at System.Threading.Tasks.Parallel.<>c__DisplayClass21`2.b__17(Int32 i) 
at System.Threading.Tasks.Parallel.<>c__DisplayClassf`1.b__c() 
at System.Threading.Tasks.Task.InnerInvoke() 
at System.Threading.Tasks.Task.InnerInvokeWithArg(Task childTask) 
at System.Threading.Tasks.Task.<>c__DisplayClass7.b__6(Object )