SyntaxError: Unexpected token C in JSON at position 1

Hi guys! I hope you can help me out!

Woo Commerce asked me to update its database seems that nothing is working since then.

The titel of the topic is the error message you get when placing an order in the store.
I am not able to choose anything within my products andymore. If I click on e.g. variations nothing happens.
I disabled all the plugins (germanized, stripe gateway, etc.) but nothing changes.

Here’s my system status:

### WordPress Environment ###

Home URL: https://www.secretrivers.com
Site URL: https://www.secretrivers.com
WC Version: 3.0.0
Log Directory Writable: ?
WP Version: 4.7.3
WP Multisite: –
WP Memory Limit: 128 MB
WP Debug Mode: –
WP Cron: ?
Language: en_US

### Server Environment ###

Server Info: Apache
PHP Version: 5.6.30
PHP Post Max Size: 200 MB
PHP Time Limit: 30
PHP Max Input Vars: 10000
cURL Version: 7.52.1
OpenSSL/1.0.1e

SUHOSIN Installed: ?
MySQL Version: ? 5.5.54 - We recommend a minimum MySQL version of 5.6. See: WordPress requirements
Max Upload Size: 200 MB
Default Timezone is UTC: ?
fsockopen/cURL: ?
SoapClient: ?
DOMDocument: ?
GZip: ?
Multibyte String: ?
Remote Post: ?
Remote Get: ?

### Database ###

WC Database Version: 3.0.0
WC Database Prefix: wp_
woocommerce_sessions: ?
woocommerce_api_keys: ?
woocommerce_attribute_taxonomies: ?
woocommerce_downloadable_product_permissions: ?
woocommerce_order_items: ?
woocommerce_order_itemmeta: ?
woocommerce_tax_rates: ?
woocommerce_tax_rate_locations: ?
woocommerce_shipping_zones: ?
woocommerce_shipping_zone_locations: ?
woocommerce_shipping_zone_methods: ?
woocommerce_payment_tokens: ?
woocommerce_payment_tokenmeta: ?
MaxMind GeoIP Database: ?

### Security ###

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

### Active Plugins (30) ###

Polylang: by Frédéric Demarle – 2.1.2
Ultimate Addons for Visual Composer: by Brainstorm Force – 3.16.9
Booking Calendar: by wpdevelop – 7.0
SiteOrigin Widgets by CodeLights: by CodeLights – 1.1.4
Duplicate Post: by Enrico Battocchi – 3.1.2
Google Tag Manager for WordPress: by Thomas Geiger – 1.5.1
Enhanced Media Library: by wpUXsolutions – 2.4.4
Instagram Feed: by Smash Balloon – 1.4.8
WPBakery Visual Composer: by Michael M - WPBakery.com – 5.1
MailChimp for WordPress: by ibericode – 4.1.0
WooCommerce Product Carousel Slider: by ADL Plugins – 2.0
Regenerate Thumbnails: by Alex Mills (Viper007Bond) – 2.2.6
Remove Query Strings From Static Resources: by Speed Up My Website
Your WP Expert – 1.4

Slider Revolution: by ThemePunch – 5.4.1
SI Captcha Anti-Spam: by Mike Challis – 3.0.0.8
UpdraftPlus - Backup/Restore: by UpdraftPlus.Com
DavidAnderson – 1.12.40

UpSolution Header Builder: by UpSolution – 1.0.3
Hyyan WooCommerce Polylang Integration: by Hyyan Abo Fakher – 0.29.1
WooCommerce Auto Restore Stock: by Gerhard Potgieter – 1.0.1
WooCommerce Stripe Gateway: by WooCommerce – 3.1.6
WooCommerce Germanized: by Vendidero – 1.8.8
WooCommerce PDF Invoices & Packing Slips: by Ewout Fernhout – 1.6.1
Woocommerce Products Per Page: by Jeroen Sormani – 1.2.2
WooCommerce: by Automattic – 3.0.0
Wordfence Security: by Wordfence – 6.3.5
Yoast SEO: by Team Yoast – 4.5
WP Fastest Cache Premium: by Emre Vona – 1.3.4
WP Fastest Cache: by Emre Vona – 0.8.6.7
WP-Optimize: by David Anderson
Ruhani Rabin
Team Updraft – 2.1.1

WP Updates Notifier: by Scott Cariss – 1.4.4

### Settings ###

API Enabled: ?
Force SSL: ?
Currency: EUR (€)
Currency Position: right
Thousand Separator: .
Decimal Separator: ,
Number of Decimals: 2
Taxonomies: Product Types: external (external)
grouped (grouped)
simple (simple)
variable (variable)

### WC Pages ###

Shop base: #1050 - /store/
Cart: #1060 - /cart/
Checkout: #1061 - /checkout/
My account: #1062 - /my-account/

### Theme ###

Name: Impreza Child
Version: 1.9
Author URL: https://us-themes.com/
Child Theme: ?
Parent Theme Name: Impreza
Parent Theme Version: 4.2
Parent Theme Author URL: https://us-themes.com/
WooCommerce Support: ?

### Templates ###

Overrides: –