PHP Fatal error: undefined function igbinary_unserialize()

I upgraded a debian 9 machine from php 7.0 to php 7.1 and now I get the following error when running wp plugin update –all or similar via wp-cli

`
PHP Fatal error: Uncaught Error: Call to undefined function igbinary_unserialize() in /home/admin/web/public_html/wp-content/object-cache.php:1123
Stack trace:
#0 /home/admin/web/public_html/wp-content/object-cache.php(740): WP_Object_Cache->maybe_unserialize(‘\x00\x00\x00\x02\x05’)
#1 /home/admin/web/public_html/wp-content/object-cache.php(128): WP_Object_Cache->get(‘is_blog_install…’, ”, false, true)
#2 /home/admin/web/public_html/wp-includes/functions.php(1524): wp_cache_get(‘is_blog_install…’)
#3 /home/admin/web/public_html/wp-includes/load.php(615): is_blog_installed()
#4 /home/admin/web/public_html/wp-settings.php(144): wp_not_installed()
#5 phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Runner.php(1209): require(‘/home/admin/web…’)
#6 phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Runner.php(1130): WP_CLI\Runner->load_wordpress()
#7 phar:/ in /home/admin/web/public_html/wp-content/object-cache.php on line 1123
`

If I rename object-cache.php to object-cache.php.bak then wp-cli works fine again…

php-redis is version 3.1.1-1 and wp-cli is version 2.2.0

Do you guys have any suggestions? Thanks!