Magento 2.3.5 checkout issue internal error 500

[diego_zanotti]

Hi community,

I'm quite new in Magento and I have this problem: in one page checkout (/checkout/#payment), selecting a payment method and click on PAY button I receive every time internal server error.. (plugins are correctly installed via Composer). 
Error notification is for example: 

Internal Error. Details are available in Magento log file. Report ID: webapi-5f9f29e6d0581

and in console error I have this:

[Error] Failed to load resource: the server responded with a status of 500 (Internal Server Error) (payment-information, line 0)

https://00up.app/magento2/rest/default/V1/guest-carts/vxhSU7GBqLQ9meSfbLpFHpEuR2fkTTXA/payment-infor...

in exception.log error is:

[2020-11-05 19:01:50] main.CRITICAL: Report ID: webapi-5fa44c1e56929; Message: Validate class not found from basename 'Magento\Framework\Validator\EmailAddress' {"exception":"[object] (Exception(code: 0): Report ID: webapi-5fa44c1e56929; Message: Validate class not found from basename 'Magento\\Framework\\Validator\\EmailAddress' at /var/www/vhosts/00up.app/httpdocs/magento2/vendor/magento/framework/Webapi/ErrorProcessor.php:208, Zend_Validate_Exception(code: 0): Validate class not found from basename 'Magento\\Framework\\Validator\\EmailAddress' at /var/www/vhosts/00up.app/httpdocs/magento2/vendor/magento/zendframework1/library/Zend/Validate.php:244)"} []

appreciate your help!
thank you

[gaurav_harsh1]

@diego_zanotti 

Try the solution provided here :

https://github.com/magento/magento2/issues/12255

Let me know if it works for you !

[maxinemccoa3e0]

I have been speaking with the developer of the theme I am using (AVADA) and he has told me the issue I am having is actually being caused by the Woo Commerce plugin.

The issue I am having is an ‘Internal Server Error’, only when a customer ticks the ‘Create an Account’ box during checkout.

[info00upitcbfa]

Thank you, but here we are talking about Mag

---

@maxinemccoa3e0 wrote:

I have been speaking with the developer of the theme I am using (AVADA) and he has told me the issue I am having is actually being caused by the Woo Commerce plugin.

The issue I am having is an ‘Internal Server Error’, only when a customer ticks the ‘Create an Account’ box during checkout.

---

ento , not WooCommerce...

[info00upitcbfa]

Thank you!!! Will try your solution and reply as soon as I can