I have upgraded cms from 10.10.4 to 11.20.3. Also I upgraded data using updateDatabaseSchema="true" in web.config file.

Now I am getting below error. Please suggest.

[ArgumentNullException: Value cannot be null.
Parameter name: type]
   System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes) +12819127
   System.Activator.CreateInstance(Type type, Object[] args) +22
   EPiServer.Shell.Modules.ModuleFinder.GetModuleInDirectory(String routeBasePath, String moduleResourcePath, IEnumerable`1 configuredAssemblyNames, AutoDiscoveryLevel discoveryMode, String configuredName) +486
   EPiServer.Shell.Modules.<>c__DisplayClass14_0.<GetModulesInSubdirectories>b__0(VirtualDirectory moduleDirectory) +117
   System.Threading.Tasks.<>c__DisplayClass42_0`2.<PartitionerForEachWorker>b__1() +1324
   System.Threading.Tasks.Task.InnerInvoke() +74
   System.Threading.Tasks.Task.InnerInvokeWithArg(Task childTask) +18
   System.Threading.Tasks.<>c__DisplayClass176_0.<ExecuteSelfReplicating>b__0(Object <p0>) +209

[AggregateException: One or more errors occurred.]
   System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions) +4246598
   System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken) +12585061
   System.Threading.Tasks.Task.Wait() +16
   System.Threading.Tasks.Parallel.PartitionerForEachWorker(Partitioner`1 source, ParallelOptions parallelOptions, Action`1 simpleBody, Action`2 bodyWithState, Action`3 bodyWithStateAndIndex, Func`4 bodyWithStateAndLocal, Func`5 bodyWithEverything, Func`1 localInit, Action`1 localFinally) +980
   System.Threading.Tasks.Parallel.ForEachWorker(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) +374
   System.Threading.Tasks.Parallel.ForEach(IEnumerable`1 source, Action`1 body) +113
   EPiServer.Shell.Modules.ModuleFinder.GetModulesInSubdirectories(String rootPath, AutoDiscoveryLevel discoveryMode) +282
   EPiServer.Packaging.Utility.PackagingModuleProvider.GetModules() +168
   EPiServer.Shell.<>c.<GetConfiguredModules>b__16_0(IModuleProvider p) +10
   System.Linq.<SelectManyIterator>d__17`2.MoveNext() +328
   System.Collections.Generic.List`1..ctor(IEnumerable`1 collection) +246
   System.Linq.Enumerable.ToList(IEnumerable`1 source) +61
   EPiServer.Shell.Modules.ShellModule.MergeDuplicateModules(IEnumerable`1 modules) +34
   EPiServer.Shell.ShellInitialization.GetConfiguredModules(IServiceLocator locator) +108
   EPiServer.Shell.ShellInitialization.Initialize(InitializationEngine context) +160
   EPiServer.Framework.Initialization.Internal.<>c__DisplayClass2_0.<Initialize>b__0() +19
   EPiServer.Framework.Initialization.Internal.ModuleNode.Execute(Action a, String key) +52
   EPiServer.Framework.Initialization.Internal.ModuleNode.Initialize(InitializationEngine context) +80
   EPiServer.Framework.Initialization.InitializationEngine.InitializeModules() +179

[InitializationException: Initialize action failed for Initialize on class EPiServer.Shell.ShellInitialization, EPiServer.Shell, Version=11.32.0.0, Culture=neutral, PublicKeyToken=8fe83dea738b45b7]
   EPiServer.Framework.Initialization.InitializationEngine.InitializeModules() +482
   EPiServer.Framework.Initialization.InitializationEngine.ExecuteTransition(Boolean continueTransitions) +153
   EPiServer.Framework.Initialization.InitializationEngine.Initialize() +40
   EPiServer.Framework.Initialization.<>c.<FrameworkInitialization>b__7_0(InitializationEngine e) +9
   EPiServer.Framework.Initialization.InitializationModule.EngineExecute(HostType hostType, Action`1 engineAction) +460
   EPiServer.Framework.Initialization.InitializationModule.FrameworkInitialization(HostType hostType) +170
   EPiServer.Global..ctor() +43
   EPiServer.Templates.Alloy.Global..ctor() +29
   ASP.global_asax..ctor() +38

[TargetInvocationException: Exception has been thrown by the target of an invocation.]
   System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck) +0
   System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark) +122
   System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark) +239
   System.Activator.CreateInstance(Type type, Boolean nonPublic) +85
   System.RuntimeType.CreateInstanceImpl(BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes, StackCrawlMark& stackMark) +1173
   System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes) +130
   System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture) +21
   System.Web.HttpRuntime.CreateNonPublicInstance(Type type, Object[] args) +63
   System.Web.HttpApplicationFactory.GetSpecialApplicationInstance(IntPtr appContext, HttpContext context) +153
   System.Web.Hosting.PipelineRuntime.InitializeApplication(IntPtr appContext) +314

[HttpException (0x80004005): Exception has been thrown by the target of an invocation.]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +10085064
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +99
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +263