I'm pretty sure I installed Drush 8 correctly on Windows 10. I ran the command window as administrator. I changed to my Drupal directory, but I get "Command pm-update needs a higher bootstrap level to run - you will need to invoke drush from a more functional Drupal environment to run this command. The drush command 'pm-update' could not be executed. Drush was not able to start (bootstrap) the Drupal database. Following are all the messages & commands I entered.
ColorConsole [Version 2.4.2000 ] Microsoft Windows [Version 10.0.14393] (c) 2016 Microsoft Corporation. All rights reserved.
C:\Users\samst\Downloads>cd C:\xampp\htdocs\D8
C:\xampp\htdocs\D8>drush status Drupal version : 8.2.4
Site URI : http://default
Database driver : mysql
Database hostname : localhost
Database port :
Database username : root
Database name : d8
PHP configuration : C:\xampp\php\php.ini
PHP OS : WINNT
Drush script : C:/Users/samst/AppData/Roaming/Composer/vendor/drush/drush/drush.php
Drush version : 8.1.5
Drush temp directory : C:\Users\samst\AppData\Local\Temp
Drush configuration :
Drush alias files :
Drupal root : C:\xampp\htdocs\D8
Drupal Settings File : sites/default/settings.php
Site path : sites/default
Sync config path : sites/default/files/config_zKz1ApBZ7jZluMMX-WwnTZyMM0eVUEH6DkWwb6HxM_V0Y0izLCsKyaGVKs7EDZiAE FFWlaSJ4g/sync
C:\xampp\htdocs\D8>drush drush pm-update The drush command 'drush pm-update' could not be found. Run drush cache-clear drush to clear the [error] commandfile cache if you have installed new extensions. Drush was not able to start (bootstrap) the Drupal database. [error] Hint: This may occur when Drush is trying to: * bootstrap a site that has not been installed or does not have a configured database. In this case you can select another site with a working database setup by specifying the URI to use with the --uri parameter on the command line. See drush topic docs-aliases for details. * connect the database through a socket. The socket file may be wrong or the php-cli may have no access to it in a jailed shell. See http://drupal.org/node/1428638 for details.
Drush was attempting to connect to: Drupal version : 8.2.4
Site URI : http://default
Database driver : mysql
Database hostname : localhost
Database port :
Database username : root
Database name : d8
PHP configuration : C:\xampp\php\php.ini
PHP OS : WINNT
Drush script : C:/Users/samst/AppData/Roaming/Composer/vendor/drush/drush/drush.php
Drush version : 8.1.5
Drush temp directory : C:\Users\samst\AppData\Local\Temp
Drush configuration :
Drush alias files :
Drupal root : C:\xampp\htdocs\D8
Drupal Settings File : sites/default/settings.php
Site path : sites/default
Sync config path : sites/default/files/config_zKz1ApBZ7jZluMMX-WwnTZyMM0eVUEH6DkWwb6HxM_V0Y0izLCsKy aGVKs7EDZiAEFFWlaSJ4g/sync
C:\xampp\htdocs\D8>drush cache-clear drush 'drush' cache was cleared. [success]
C:\xampp\htdocs\D8>drush pm-update Command pm-update needs a higher bootstrap level to run - you will need to invoke drush from a more [error] functional Drupal environment to run this command. The drush command 'pm-update' could not be executed. [error] Drush was not able to start (bootstrap) the Drupal database. [error] Hint: This may occur when Drush is trying to: * bootstrap a site that has not been installed or does not have a configured database. In this case you can select another site with a working database setup by specifying the URI to use with the --uri parameter on the command line. See drush topic docs-aliases for details. * connect the database through a socket. The socket file may be wrong or the php-cli may have no access to it in a jailed shell. See http://drupal.org/node/1428638 for details.
Drush was attempting to connect to: Drupal version : 8.2.4
Site URI : http://default
Database driver : mysql
Database hostname : localhost
Database port :
Database username : root
Database name : d8
PHP configuration : C:\xampp\php\php.ini
PHP OS : WINNT
Drush script : C:/Users/samst/AppData/Roaming/Composer/vendor/drush/drush/drush.php
Drush version : 8.1.5
Drush temp directory : C:\Users\samst\AppData\Local\Temp
Drush configuration :
Drush alias files :
Drupal root : C:\xampp\htdocs\D8
Drupal Settings File : sites/default/settings.php
Site path : sites/default
Sync config path : sites/default/files/config_zKz1ApBZ7jZluMMX-WwnTZyMM0eVUEH6DkWwb6HxM_V0Y0izLCsKy aGVKs7EDZiAEFFWlaSJ4g/sync
C:\xampp\htdocs\D8>
I am running D8 with XAMPP on Windows 10. I've spent a significant amount of time searching the web for a solution. I tried changing the 'host' line in settings.php. That did not help.