Unable to install extensions in Visual studio 2019 and it fails with error Invalid TimeStamp or Digital Signature as none - visual-studio-extensions

Question

I am unable to install most of the Visual studio extensions(Ex: Episerver, NPM Task runner). During the installation it shows “Digital Signature: Invalid TimeStamp” or “Digital Signature: Null”. Although for some extensions it is showing “Digital Signature: Invalid TimeStamp” but it successfully completes the installation.(Ex: Microsoft visual studio installer projects)
Visual studio Community edition version: 16.6.5 (2019).
Below is the error log:
8/7/2020 10:12:29 AM - Capping recursion at 5 directories in each extension root due to 'default limit'.
8/7/2020 10:12:29 AM - Found 'C:\USERS\SARRMARPA\APPDATA\LOCAL\MICROSOFT\VISUALSTUDIO\16.0_6EE4662A\EXTENSIONS\pondhjej.glj\extension.vsixmanifest'
8/7/2020 10:12:29 AM - Found 'C:\PROGRAM FILES (X86)\COMMON FILES\MICROSOFT\EXTENSIONMANAGER\EXTENSIONS\Microsoft\Windows Kits\10\Desktop SDK\extension.vsixmanifest'
8/7/2020 10:12:29 AM - Found 'C:\PROGRAM FILES (X86)\COMMON FILES\MICROSOFT\EXTENSIONMANAGER\EXTENSIONS\Microsoft\Windows Kits\10\SDK ARM Additions\extension.vsixmanifest'
8/7/2020 10:12:29 AM - Found 'C:\PROGRAM FILES (X86)\COMMON FILES\MICROSOFT\EXTENSIONMANAGER\EXTENSIONS\Microsoft\Windows Kits\10\Windows Store SDK\extension.vsixmanifest'
8/7/2020 10:12:29 AM - Skipping 'C:\Users\sarrmarpa\AppData\Local\Microsoft SDKs' as it doesn't exist
8/7/2020 10:12:29 AM - Beginning to install extension to Microsoft Visual Studio Professional 2019...
8/7/2020 10:12:29 AM - VSIX TaskScheduler: VSIX Update Configuration task has not been successfully registered.
8/7/2020 10:12:29 AM - No mapping between account names and security IDs was done
8/7/2020 10:13:18 AM - Skipping non-applicable package Microsoft.Windows.UniversalCRT.Msu.8: The current OS Version '6.3.9600.0' is not in the supported version range '[6.2,6.3)'.
8/7/2020 10:13:18 AM - Skipping non-applicable package Microsoft.VisualStudio.NuGet.PowershellBindingRedirect: The current OS Version '6.3.9600.0' is not in the supported version range '[6.1,6.2)'.
8/7/2020 10:13:18 AM - Skipping non-applicable package Microsoft.Windows.UniversalCRT.Msu.7: The current OS Version '6.3.9600.0' is not in the supported version range '[6.1,6.2)'.
8/7/2020 10:13:18 AM - Skipping non-applicable package Microsoft.DiagnosticsHub.KB2882822.Win7: The current OS Version '6.3.9600.0' is not in the supported version range '[6.1,6.2)'.
8/7/2020 10:13:18 AM - Skipping non-applicable package Microsoft.Azure.PowerShellNew: Required conditions are not satisfied: Powershell5
8/7/2020 10:13:18 AM - Skipping non-applicable package Microsoft.VisualStudio.Graphics.EnableTools: The current OS Version '6.3.9600.0' is not in the supported version range '10.0.10240'.
8/7/2020 10:13:19 AM - Skipping non-applicable package Microsoft.VisualStudio.OfficeDeveloperTools.WindowsIdentityFoundation.Msu: The current OS Version '6.3.9600.0' is not in the supported version range '(,6.2)'.
8/7/2020 10:13:19 AM - System restore is not supported on this system
8/7/2020 10:13:19 AM - Failed to create system restore point: 0x80131524
8/7/2020 10:13:44 AM - Certificate is invalid: EPiServer.VsIntegration.Package.vsix
8/7/2020 10:13:44 AM - Cache failed. Retrying download of 'EPiServer.CMS.B7A45E5E-3836-4864-A117-95207E71A9B3,version=11.7.0.437'.
8/7/2020 10:13:44 AM - Value cannot be null.
Parameter name: uri
8/7/2020 10:13:44 AM - Value cannot be null.
Parameter name: uri
8/7/2020 10:13:44 AM - Activity threw exception System.ArgumentNullException: Value cannot be null.
Parameter name: uri
8/7/2020 10:13:44 AM - Skipping cache of package 'EPiServer.CMS.B7A45E5E-3836-4864-A117-95207E71A9B3,version=11.7.0.437' since installing or downloading it failed
8/7/2020 10:13:44 AM - Skipping cache of package 'Component.EPiServer.CMS.B7A45E5E-3836-4864-A117-95207E71A9B3,version=11.7.0.437' since the package or a parent package had a vital failure.
8/7/2020 10:14:17 AM - Install Error : System.AggregateException: One or more errors occurred. ---> Microsoft.VisualStudio.Setup.PackageFailureException: Package 'EPiServer.CMS.B7A45E5E-3836-4864-A117-95207E71A9B3' failed to download
at Microsoft.VisualStudio.Setup.InstallOperation.Run(CancellationToken token)
at Microsoft.VisualStudio.Setup.Engine.RunOperation(InstallOperation installOperation, CancellationToken token, ExecuteAction action, ITelemetryOperation telemetryOperation)
at Microsoft.VisualStudio.Setup.Engine.RunCoreOperation(InstallOperation coreOperation, ExecuteAction action, ITelemetryOperation telemetryOperation, CancellationToken token)
at Microsoft.VisualStudio.Setup.Engine.Install(Product product, String destination, CancellationToken token)
at Microsoft.VisualStudio.ExtensionManager.SetupEngineService.b__14_0()
at System.Threading.Tasks.Task1.InnerInvoke() at System.Threading.Tasks.Task.Execute() --- 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 Microsoft.VisualStudio.ExtensionManager.SetupEngineService.Install() at Microsoft.VisualStudio.ExtensionManager.ExtensionEngineImpl.PerformSetupEngineInstall(InstallableExtensionImpl extension, Boolean installPerMachine, Boolean isPackComponent, IDictionary2 extensionsInstalledSoFar, List1 extensionsUninstalledSoFar, IInstalledExtensionList modifiedInstalledExtensionsList, IProgress1 progress, InstallFlags installFlags, AsyncOperation asyncOp, Version targetedVsVersion, IInstalledExtension& newExtension)
at Microsoft.VisualStudio.ExtensionManager.ExtensionEngineImpl.InstallInternal(InstallableExtensionImpl extension, InstallFlags installFlags, IDictionary2 extensionsInstalledSoFar, List1 extensionsUninstalledSoFar, IInstalledExtensionList modifiedInstalledExtensionsList, AsyncOperation asyncOp, IProgress1 progress, Version targetedVsVersion) at Microsoft.VisualStudio.ExtensionManager.ExtensionEngineImpl.BeginInstall(IInstallableExtension installableExtension, InstallFlags installFlags, AsyncOperation asyncOp, Version targetedVsVersion) at Microsoft.VisualStudio.ExtensionManager.ExtensionEngineImpl.InstallWorker(IInstallableExtension extension, InstallFlags installFlags, AsyncOperation asyncOp) ---> (Inner Exception #0) Microsoft.VisualStudio.Setup.PackageFailureException: Package 'EPiServer.CMS.B7A45E5E-3836-4864-A117-95207E71A9B3' failed to download at Microsoft.VisualStudio.Setup.InstallOperation.Run(CancellationToken token) at Microsoft.VisualStudio.Setup.Engine.RunOperation(InstallOperation installOperation, CancellationToken token, ExecuteAction action, ITelemetryOperation telemetryOperation) at Microsoft.VisualStudio.Setup.Engine.RunCoreOperation(InstallOperation coreOperation, ExecuteAction action, ITelemetryOperation telemetryOperation, CancellationToken token) at Microsoft.VisualStudio.Setup.Engine.Install(Product product, String destination, CancellationToken token) at Microsoft.VisualStudio.ExtensionManager.SetupEngineService.<Install>b__14_0() at System.Threading.Tasks.Task1.InnerInvoke()
at System.Threading.Tasks.Task.Execute()<---

Answer 1

Unable to install extensions in Visual studio 2019 and it fails with
error Invalid TimeStamp or Digital Signature as none
Please try the following steps to troubleshoot your issue:
1) go to the path C:\Program Files (x86)\Microsoft Visual Studio\2019\Community \Common7\IDE\PublicAssemblies and check if you have this dll
Microsoft.VisualStudio.DeployWizard.dll
enter C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\Common7\IDE and check if you have this dll
Microsoft.VisualStudio.WizardFramework.dll
Then, please rename these two dlls to other names or just delete them.
After that, restart your computer to test again.
Also, enter C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\Common7\IDE\CommonExtensions\Microsoft and check if you has a folder called VSI.
If so, please rename this folder to another name or just delete it.
2) disable any VS third party extensions under Extensions-->Manage Extensions
3) turn off any third party software, anti-virus and firewall
4) reset VS settings
5) repair VS in the VS Installer or if there is new release vs version, please update VS.
Also, check if you have any OS update, if so, please update it.
6) delete any C:\Users\xxx(current user)\AppData\Local\Microsoft\VisualStudio\16.0_xxxx folders and then restart VS to test again.
7) At last, if all the steps do not work, reinstalling VS might be a choice. Although it will spend lots of time, I think you could have a try.