Hi,

We're getting an error out of the blue with our production 8.17.1 site. It gives a yellow screen of death with the following when trying to access any page or the backend:

Exception information: 
    Exception type: ArgumentOutOfRangeException 
    Exception message: Specified argument was out of the range of valid values.
Parameter name: handle
   at CSharpTest.Net.IO.TransactedCompoundFile.Read(UInt32 handle)
   at CSharpTest.Net.Storage.BTreeFileStoreV2.TryGetNode[TNode](IStorageHandle handleIn, TNode& node, ISerializer`1 serializer)
   at CSharpTest.Net.Collections.BPlusTree`2.StorageCache.FetchFromStore`1.CreateValue(IStorageHandle key, Object& value)
   at CSharpTest.Net.Collections.LurchTable`2.InternalInsert[T](Int32 hash, TKey key, Int32& added, T& value)
   at CSharpTest.Net.Collections.LurchTable`2.Insert[T](TKey key, T& value)
   at CSharpTest.Net.Collections.LurchTable`2.AddOrUpdate[T](TKey key, T& createOrUpdateValue)
   at CSharpTest.Net.Collections.BPlusTree`2.StorageCache.TryGetNode[TNode](IStorageHandle handle, TNode& tnode, ISerializer`1 serializer)
   at CSharpTest.Net.Collections.BPlusTree`2.NodeCacheNone.Lock(NodePin parent, LockType ltype, NodeHandle child)
   at CSharpTest.Net.Collections.BPlusTree`2.Enumerator.SeekNext(NodePin thisLock, TKey key, NodePin& pin, Int32& offset, TKey& nextKey, Boolean& hasMore)
   at CSharpTest.Net.Collections.BPlusTree`2.Enumerator.MoveNext()
   at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
   at System.Linq.Buffer`1..ctor(IEnumerable`1 source)
   at System.Linq.OrderedEnumerable`1.<GetEnumerator>d__1.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at Umbraco.Web.PublishedCache.NuCache.PublishedSnapshotService.LoadEntitiesFromLocalDbLocked(Boolean onStartup, BPlusTree`2 localDb, ContentStore store, String entityType)
   at Umbraco.Web.PublishedCache.NuCache.PublishedSnapshotService.LoadContentFromLocalDbLocked(Boolean onStartup)
   at Umbraco.Web.PublishedCache.NuCache.PublishedSnapshotService.LockAndLoadContent(Func`2 action)
   at Umbraco.Web.PublishedCache.NuCache.PublishedSnapshotService.<EnsureCaches>b__36_0()
   at System.Threading.LazyInitializer.EnsureInitializedCore[T](T& target, Boolean& initialized, Object& syncLock, Func`1 valueFactory)
   at Umbraco.Web.PublishedCache.NuCache.PublishedSnapshotService.EnsureCaches()
   at Umbraco.Web.PublishedCache.NuCache.PublishedSnapshotService.CreatePublishedSnapshot(String previewToken)
   at System.Lazy`1.CreateValue()
   at System.Lazy`1.LazyInitValue()
   at Umbraco.Web.UmbracoInjectedModule.EnsureHasContent(UmbracoContext context, HttpContextBase httpContext)
   at Umbraco.Web.UmbracoInjectedModule.EnsureUmbracoRoutablePage(UmbracoContext context, HttpContextBase httpContext)
   at Umbraco.Web.UmbracoInjectedModule.ProcessRequest(HttpContextBase httpContext)
   at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step)
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

It seems to be difficult to find information about what causes this error and how to fix it. I've tried clearing the cache and TEMP directories, restarting the IIS site, and restarting the IIS server, ensuring that w3wp.exe isn't running, and various combinations thereof. I've confirmed from modification dates that nobody's messed around with bin or Web.config. I've checked the file permissions. The drives are nowhere near full.

Any ideas?