Issue:
Few times we came across the issue of failing of D365 apply updates or package deployment failed at the step of DevTools.

Resolution:
To resolve the issue follow below steps:
- Download the package if not downloaded
- Unblock the downloaded package Zip file before extracting
- Extract the the package zip file
- Navigate to the DevToolsService/Scripts folder in the extracted package folder
- Find the the file Microsoft.Dynamics.Framework.Tools.Installer


- Double click on the file and install the extension for VS2019

- Once extension installation complete resume the package deployment.
Please feel free to comment if you’re facing any issue. We will try our best to help you solve the issues.