“Next Step” button not working

Hello,

I have a problem with the “Next Step” button, when i want to click on next step nothing happens. I checked my error log and i do recieve this error:
[23/Aug/2022:10:38:01 +0200] “POST /wp-admin/admin-ajax.php?action=wpcf7cf_validate_step HTTP/1.1” 500 178 “https://xxxxxx.be/test/” “Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36”

I did some research but nothing seems to work, can you help me please?
Code in form test: http://conditional-fields-cf7.bdwm.be/form-tester/?hash=412550e7bd25c9904ba485a19b5b682f

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Kind regards,
Ray