Failed OC server update

Please help us by providing the following info. Before posting please also check the pinned "Known issues" threads and make sure that you're running the latest available version for your oC release: https://owncloud.org/changelog/

Steps to reproduce
1. Update OC server from last version of 9.x to OC 10
2. Upgrade PHP to version 5.6.30-10+deb.sury.org~trusty+2
3. sudo -u www-data php occ upgrade

Expected behaviour
Tell us what should happen
Owncloud server should have upgraded and run

Actual behaviour
Tell us what happens instead
$ sudo -u www-data php occ upgrade
results in:
An unhandled exception has been thrown:
exception 'Doctrine\DBAL\DBALException' with message 'Failed to connect to the database: An exception occured in driver: could not find driver' in /var/www/owncloud/lib/private/DB/Connection.php:63
Stack trace:

0 /var/www/owncloud/lib/composer/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(429): OC\DB\Connection->connect()

1 /var/www/owncloud/lib/composer/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(389): Doctrine\DBAL\Connection->getDatabasePlatformVersion()

2 /var/www/owncloud/lib/composer/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(328): Doctrine\DBAL\Connection->detectDatabasePlatform()

3 /var/www/owncloud/lib/composer/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(623): Doctrine\DBAL\Connection->getDatabasePlatform()

4 /var/www/owncloud/lib/private/DB/Connection.php(146): Doctrine\DBAL\Connection->setTransactionIsolation(2)

5 /var/www/owncloud/lib/composer/doctrine/dbal/lib/Doctrine/DBAL/DriverManager.php(172): OC\DB\Connection->__construct(Array, Object(Doctrine\DBAL\Driver\PDOMySql\Driver), Object(Doctrine\DBAL\Configuration), Object(Doctrine\Common\EventManager))

6 /var/www/owncloud/lib/private/DB/ConnectionFactory.php(138): Doctrine\DBAL\DriverManager::getConnection(Array, Object(Doctrine\DBAL\Configuration), Object(Doctrine\Common\EventManager))

7 /var/www/owncloud/lib/private/Server.php(461): OC\DB\ConnectionFactory->getConnection('mysql', Array)

8 /var/www/owncloud/lib/composer/pimple/pimple/src/Pimple/Container.php(113): OC\Server->OC{closure}(Object(OC\Server))

9 /var/www/owncloud/lib/private/AppFramework/Utility/SimpleContainer.php(111): Pimple\Container->offsetGet('DatabaseConnect...')

10 /var/www/owncloud/lib/private/ServerContainer.php(87): OC\AppFramework\Utility\SimpleContainer->query('DatabaseConnect...')

11 /var/www/owncloud/lib/private/Server.php(1101): OC\ServerContainer->query('DatabaseConnect...')

12 /var/www/owncloud/lib/private/Server.php(226): OC\Server->getDatabaseConnection()

13 /var/www/owncloud/lib/composer/pimple/pimple/src/Pimple/Container.php(113): OC\Server->OC{closure}(Object(OC\Server))

14 /var/www/owncloud/lib/private/AppFramework/Utility/SimpleContainer.php(111): Pimple\Container->offsetGet('UserManager')

15 /var/www/owncloud/lib/private/ServerContainer.php(87): OC\AppFramework\Utility\SimpleContainer->query('UserManager')

16 /var/www/owncloud/lib/private/Server.php(953): OC\ServerContainer->query('UserManager')

17 /var/www/owncloud/lib/private/Server.php(267): OC\Server->getUserManager()

18 /var/www/owncloud/lib/composer/pimple/pimple/src/Pimple/Container.php(113): OC\Server->OC{closure}(Object(OC\Server))

19 /var/www/owncloud/lib/private/AppFramework/Utility/SimpleContainer.php(111): Pimple\Container->offsetGet('UserSession')

20 /var/www/owncloud/lib/private/ServerContainer.php(87): OC\AppFramework\Utility\SimpleContainer->query('UserSession')

21 /var/www/owncloud/lib/private/Server.php(970): OC\ServerContainer->query('UserSession')

22 /var/www/owncloud/lib/private/Server.php(507): OC\Server->getUserSession()

23 /var/www/owncloud/lib/composer/pimple/pimple/src/Pimple/Container.php(113): OC\Server->OC{closure}(Object(OC\Server))

24 /var/www/owncloud/lib/private/AppFramework/Utility/SimpleContainer.php(111): Pimple\Container->offsetGet('AppManager')

25 /var/www/owncloud/lib/private/ServerContainer.php(87): OC\AppFramework\Utility\SimpleContainer->query('AppManager')

26 /var/www/owncloud/lib/private/Server.php(1288): OC\ServerContainer->query('AppManager')

27 /var/www/owncloud/lib/private/legacy/app.php(310): OC\Server->getAppManager()

28 /var/www/owncloud/lib/private/legacy/app.php(106): OC_App::getEnabledApps()

29 /var/www/owncloud/lib/base.php(579): OC_App::loadApps(Array)

30 /var/www/owncloud/lib/base.php(994): OC::init()

31 /var/www/owncloud/console.php(57): require_once('/var/www/ownclo...')

32 /var/www/owncloud/occ(11): require_once('/var/www/ownclo...')

33 {main}PHP Fatal error: Uncaught exception 'Doctrine\DBAL\DBALException' with message 'Failed to connect to the database: An exception occured in driver: could not find driver' in /var/www/owncloud/lib/private/DB/Connection.php:63

Stack trace:

0 /var/www/owncloud/lib/composer/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(429): OC\DB\Connection->connect()

1 /var/www/owncloud/lib/composer/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(389): Doctrine\DBAL\Connection->getDatabasePlatformVersion()

2 /var/www/owncloud/lib/composer/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(328): Doctrine\DBAL\Connection->detectDatabasePlatform()

3 /var/www/owncloud/lib/composer/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(623): Doctrine\DBAL\Connection->getDatabasePlatform()

4 /var/www/owncloud/lib/private/DB/Connection.php(146): Doctrine\DBAL\Connection->setTransactionIsolation(2)

5 /var/www/owncloud/lib/composer/doctrine/dbal/lib/Doctrine/DBAL/DriverManager.php(172): OC\DB\Connection->__construct(Array, Object(Doctrine\DBAL\Driver\PDOMySql\ in /var/www/owncloud/lib/private/DB/Connection.php on line 63

Server configuration
Operating system: Ubuntu 14.04 Linux Sibyl 3.13.0-117-generic #164-Ubuntu SMP Fri Apr 7 11:05:26 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
Web server: Server version: Apache/2.4.7 (Ubuntu)
Database:mysql Ver 14.14 Distrib 5.5.55, for debian-linux-gnu (x86_64) using readline 6.3
PHP version: PHP 5.6.30-10+deb.sury.org~trusty+2 (cli
ownCloud version (see ownCloud admin page): 10.0
Updated from an older ownCloud or fresh install: older version: the 9.xx version just before 10.0
Special configuration (external storage, external authentication, reverse proxy, server-side-encryption):

ownCloud configuration

Go to the admin page, click on 'admin' -> 'Generate Config Report' -> 'Download ownCloud config report' or use the command line `sudo -u www-data php occ config:list system` (please sanitize sensitive data):

ownCloud log (data/owncloud.log)

I cannot even get into my Owncloud webpage! attempts to do so give:
**This version of ownCloud requires at least PHP 5.6.0
You are currently running 5.5.9-1ubuntu4.21. Please update your PHP version.**
but $ php -v shows
PHP 5.6.30-10+deb.sury.org~trusty+2 (cli)
Copyright (c) 1997-2016 The PHP Group
Zend Engine v2.6.0, Copyright (c) 1998-2016 Zend Technologies
with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2016, by Zend Technologies
Help much appreciated!
Phil

Please paste possible errors in the following code block, see https://central.owncloud.org/t/how-to-find-webserver-or-oc-logfile-enable-php-logfile/808 for more info

Integrity status for oC9+

Login as admin user into your ownCloud and access
http://example.com/index.php/settings/integrity/failed
paste the results here.

This shows that there is a misconfiguration in your PHP environment where the database driver is not correctly loaded. Please ask for support on how to configure this correctly at the resources listed at https://secure.php.net/support.php