500 Internal Server Error

Hello, @pxforti

Thank you for posting the error log.

Please send us a WooCommerce system status. Here’s a screenshot showing how to get it.
It is a very important piece of information, necessary to find the problem.

Here is WooCommerce status:

### WordPress Environment ###

Home URL: https://woocommerce.test
Site URL: https://woocommerce.test
WC Version: 3.3.5
Log Directory Writable: ?
WP Version: 4.9.5
WP Multisite: –
WP Memory Limit: 256 MB
WP Debug Mode: ?
WP Cron: ?
Language: en_US

### Server Environment ###

Server Info: Apache
PHP Version: 7.1.12
PHP Post Max Size: 32 MB
PHP Time Limit: 0
PHP Max Input Vars: 1000
cURL Version: 7.52.1
OpenSSL/1.0.2j

SUHOSIN Installed: –
MySQL Version: 5.6.38
Max Upload Size: 32 MB
Default Timezone is UTC: ?
fsockopen/cURL: ?
SoapClient: ?
DOMDocument: ?
GZip: ?
Multibyte String: ?
Remote Post: ?
Remote Get: ?

### Database ###

WC Database Version: 3.3.5
WC Database Prefix: woowp_
MaxMind GeoIP Database: ?
Total Database Size: 2.84MB
Database Data Size: 1.82MB
Database Index Size: 1.02MB
woowp_woocommerce_sessions: Data: 0.02MB + Index: 0.02MB
woowp_woocommerce_api_keys: Data: 0.02MB + Index: 0.03MB
woowp_woocommerce_attribute_taxonomies: Data: 0.02MB + Index: 0.02MB
woowp_woocommerce_downloadable_product_permissions: Data: 0.02MB + Index: 0.05MB
woowp_woocommerce_order_items: Data: 0.02MB + Index: 0.02MB
woowp_woocommerce_order_itemmeta: Data: 0.02MB + Index: 0.03MB
woowp_woocommerce_tax_rates: Data: 0.02MB + Index: 0.06MB
woowp_woocommerce_tax_rate_locations: Data: 0.02MB + Index: 0.05MB
woowp_woocommerce_shipping_zones: Data: 0.02MB + Index: 0.00MB
woowp_woocommerce_shipping_zone_locations: Data: 0.02MB + Index: 0.05MB
woowp_woocommerce_shipping_zone_methods: Data: 0.02MB + Index: 0.00MB
woowp_woocommerce_payment_tokens: Data: 0.02MB + Index: 0.02MB
woowp_woocommerce_payment_tokenmeta: Data: 0.02MB + Index: 0.03MB
woowp_woocommerce_log: Data: 0.02MB + Index: 0.02MB
woowp_commentmeta: Data: 0.06MB + Index: 0.03MB
woowp_comments: Data: 0.02MB + Index: 0.09MB
woowp_links: Data: 0.02MB + Index: 0.02MB
woowp_options: Data: 1.03MB + Index: 0.05MB
woowp_postmeta: Data: 0.19MB + Index: 0.13MB
woowp_posts: Data: 0.06MB + Index: 0.06MB
woowp_termmeta: Data: 0.02MB + Index: 0.03MB
woowp_terms: Data: 0.02MB + Index: 0.03MB
woowp_term_relationships: Data: 0.02MB + Index: 0.02MB
woowp_term_taxonomy: Data: 0.02MB + Index: 0.03MB
woowp_usermeta: Data: 0.02MB + Index: 0.03MB
woowp_users: Data: 0.02MB + Index: 0.05MB
woowp_wc_download_log: Data: 0.02MB + Index: 0.03MB
woowp_wc_webhooks: Data: 0.02MB + Index: 0.02MB

### Post Type Counts ###

attachment: 52
nav_menu_item: 7
page: 6
post: 2
product: 26
product_variation: 4
revision: 10
scheduled-action: 2
shop_order: 3
shop_subscription: 2
staff-member: 2

### Security ###

Secure connection (HTTPS): ?Your store is not using HTTPS. Learn more about HTTPS and SSL Certificates.
Hide errors from visitors: ?

### Active Plugins (6) ###

BackUpWordPress: by Human Made Limited – 3.6.4
Black Studio TinyMCE Widget: by Black Studio – 2.6.2
WooCommerce Stripe Gateway: by WooCommerce – 4.1.0
WooCommerce Product Add-ons: by WooCommerce – 2.9.2
WooCommerce Subscriptions: by Prospress Inc. – 2.2.19
WooCommerce: by Automattic – 3.3.5

### Settings ###

API Enabled: ?
Force SSL: –
Currency: USD ($)
Currency Position: left
Thousand Separator: ,
Decimal Separator: .
Number of Decimals: 2
Taxonomies: Product Types: external (external)
grouped (grouped)
simple (simple)
subscription (subscription)
variable (variable)
variable subscription (variable-subscription)

Taxonomies: Product Visibility: exclude-from-catalog (exclude-from-catalog)
exclude-from-search (exclude-from-search)
featured (featured)
outofstock (outofstock)
rated-1 (rated-1)
rated-2 (rated-2)
rated-3 (rated-3)
rated-4 (rated-4)
rated-5 (rated-5)

### WC Pages ###

Shop base: #102 - /shop/
Cart: #103 - /cart/
Checkout: #104 - /checkout/
My account: #105 - /my-account/
Terms and conditions: ? Page not set

### Theme ###

Name: Storefront
Version: 2.2.8
Author URL: https://woocommerce.com/
Child Theme: ? – If you are modifying WooCommerce on a parent theme that you did not build personally we recommend using a child theme. See: How to create a child theme
WooCommerce Support: ?

### Templates ###

Overrides: –

### subscriptions ###

WCS_DEBUG: ?
						No
Subscriptions Mode: ?
						Live
Subscriptions Template Theme Overrides: –
Report Cache Enabled: ?
						Yes
Cache Update Failures: ?
						0 failure

Hi. I just updated WooCommerce Product Add-ons and WooCommerce Subscriptions and that fixed the problem.

Sorry for the trouble.