Error after switching to 18.3 Beta

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,
1

Hi,
i installed the beta version, there are some problems while installing some packages, i could not able to install like csv helper and uipath.powershell, how to install them,
and using the beta version,i am not able to access my previous artifacts(created with the older version).
18.3.0-beta.1+Branch.release/v2018.3.Sha.313cfd2253c04b9c8e037f059b32d39b857eaa6f

An internal error has occurred. It is recommended to restart UiPath Studio.

Open Document Error: UiPath.Studio.Contracts.RecoverableException —> UiPath.Studio.Contracts.RecoverableException: The project ‘D:\project.json’ could not be opened: Object reference not set to an instance of an object… —> System.NullReferenceException: Object reference not set to an instance of an object.
at UiPath.Studio.Shell.Packaging.PackageOperationRestore.<>c__DisplayClass2_0.b__0(ProjectPackage pp)
at UiPath.Studio.Shared.MVVM.CollectionExtensions.ForEach[TItem](IEnumerable1 collection, Action1 action)
at UiPath.Studio.Shell.Packaging.PackageOperationRestore.GetResult(IEnumerable1 requestedPackages, IEnumerable1 installedPackages)
at UiPath.Studio.Shell.Packaging.PackageOperationRestore.d__1.MoveNext()
— End of stack trace from previous location where exception was thrown —
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at UiPath.Studio.Shell.Packaging.PackageService.d__22.MoveNext()
— End of stack trace from previous location where exception was thrown —
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at UiPath.Studio.Plugin.Workflow.Project.WorkflowProjectModelFactory.d__34.MoveNext()
— End of stack trace from previous location where exception was thrown —
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at UiPath.Studio.Plugin.Workflow.Project.WorkflowProjectModelFactory.d__41.MoveNext()
— End of stack trace from previous location where exception was thrown —
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at UiPath.Studio.Plugin.Workflow.Project.WorkflowProjectModelFactory.d__39.MoveNext()
— End of stack trace from previous location where exception was thrown —
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at UiPath.Studio.Shell.Services.PersistableServiceBase2.<OnOpenAsync>d__22.MoveNext() --- End of inner exception stack trace --- at UiPath.Studio.Shell.Services.PersistableServiceBase2.d__22.MoveNext()
— End of stack trace from previous location where exception was thrown —
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at UiPath.Studio.Shell.Services.ProjectService.d__39.MoveNext()
— End of stack trace from previous location where exception was thrown —
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at UiPath.Studio.Shell.Services.PersistableServiceBase`2.d__15.MoveNext()
— End of stack trace from previous location where exception was thrown —
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at UiPath.Studio.Shell.Services.OpenCloseCommandsService.d__16.MoveNext()
— End of inner exception stack trace —
at UiPath.Studio.Shell.Services.OpenCloseCommandsService.d__16.MoveNext()
— End of stack trace from previous location where exception was thrown —
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at UiPath.Studio.Shell.Services.OpenCloseCommandsService.d__13.MoveNext()
— End of stack trace from previous location where exception was thrown —
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at UiPath.Studio.Shell.ApplicationStartup.d__15.MoveNext()
— End of stack trace from previous location where exception was thrown —
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at UiPath.Studio.Shell.ApplicationStartup.<b__29_0>d.MoveNext()
— End of stack trace from previous location where exception was thrown —
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<>c.b__6_0(Object state)
at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler), HResult -2146233088
please tell me how to handle this or please tell me where can i download the previous version link for which i can access my old artifacts
@ovi

Thanks