woocommerce plugin causes redirect loop

I come immediately to the point.
The woocommerce plugin and, judging by the logs, even woocommerce plugins, cause a fatal error that causes an infinite redirect loop to those who remain connected to the site, even after removing them.
Apache error logs report:
Fatal error: Uncaught Error: Call to undefined function get_woocommerce_currency() in /var/www/newkml/wordpress/wp-content/plugins/woocommerce-gateway-paypal-express-checkout/includes/class-wc-gateway-ppec-settings.php:293 Stack trace: #0 /var/www/newkml/wordpress/wp-content/plugins/woocommerce-gateway-paypal-express-checkout/includes/class-wc-gateway-ppec-plugin.php(354): WC_Gateway_PPEC_Settings->currency_has_decimal_restriction() #1 /var/www/newkml/wordpress/wp-includes/class-wp-hook.php(286): WC_Gateway_PPEC_Plugin->activate('') #2 /var/www/newkml/wordpress/wp-includes/class-wp-hook.php(310): WP_Hook->apply_filters('', Array) #3 /var/www/newkml/wordpress/wp-includes/plugin.php(465): WP_Hook->do_action(Array) #4 /var/www/newkml/wordpress/wp-admin/plugins.php(177): do_action('activate_woocom...') #5 {main} thrown in /var/www/newkml/wordpress/wp-content/plugins/woocommerce-gateway-paypal-express-checkout/includes/class-wc-gateway-ppec-settings.php on line 293
Here complaints about an another, maybe unofficial plugin:
[Fri May 17 12:22:01.189191 2019] [php7:error] [pid 13144] [client 95.216.136.47:43558] PHP Fatal error: Uncaught Error: Call to undefined function wc_get_base_location() in /var/www/newkml/wordpress/wp-content/plugins/klarna-onsite-messaging-for-woocommerce/klarna-onsite-messaging-for-woocommerce.php:156\nStack trace:\n#0 /var/www/newkml/wordpress/wp-includes/class-wp-hook.php(286): Klarna_OnSite_Messaging_For_WooCommerce->enqueue_scripts('')\n#1 /var/www/newkml/wordpress/wp-includes/class-wp-hook.php(310): WP_Hook->apply_filters(NULL, Array)\n#2 /var/www/newkml/wordpress/wp-includes/plugin.php(465): WP_Hook->do_action(Array)\n#3 /var/www/newkml/wordpress/wp-includes/script-loader.php(2537): do_action('wp_enqueue_scri...')\n#4 /var/www/newkml/wordpress/wp-includes/class-wp-hook.php(286): wp_enqueue_scripts('')\n#5 /var/www/newkml/wordpress/wp-includes/class-wp-hook.php(310): WP_Hook->apply_filters(NULL, Array)\n#6 /var/www/newkml/wordpress/wp-includes/plugin.php(465): WP_Hook->do_action(Array)\n#7 /var/www/newkml/wordpress/wp-includes/general-template.php(2746): do_action('wp_head')\n#8 /var/www/newkml/wordpress/wp-conte in /var/www/newkml/wordpress/wp-content/plugins/klarna-onsite-messaging-for-woocommerce/klarna-onsite-messaging-for-woocommerce.php on line 156
I haven’t found much on google if not examples that refer to programming knowledge that I don’t have.
I deduce that woocommerce is in conflict and I thought the cause was the recent update from php7.2 to php7.3.
I have tried all the versions, at the moment the site is with php7.0 and the error persists.
My VPS is a CX10 with debian stretch, apache2.4, php7.0 as just mentioned.
Help !
Have a nice day !

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