Problem to access to the BO: CLOSED_ALLOWED_FAILURES" is not defined

[dpo]

Hello,

I will appreciate your help. I can access to the BO (prestashop version 1.7.5.2). I get this error each time that I try to access to the BO:

(3/3) FileLoaderLoadException

The file "/home/customer/www/...com/public_html/src/PrestaShopBundle/Resources/config/services/core/currency.yml" does not contain valid YAML: The constant "\PrestaShop\PrestaShop\Core\Currency\ExchangeRateProvider::CLOSED_ALLOWED_FAILURES" is not defined at line 16 (near "- !php/const \PrestaShop\PrestaShop\Core\Currency\ExchangeRateProvider::CLOSED_ALLOWED_FAILURES") in /home/customer/www/....com/public_html/src/PrestaShopBundle/Resources/config/services/core/currency.yml (which is being imported from "/home/customer/www/...com/public_html/src/PrestaShopBundle/Resources/config/services.yml").

The web is running without problems but I can not access to the administration panel.

Curiously if I restore a backup of days ago when the web was running, I get the same error!

I have deleted manually the cache /var/cache

I will appreciate very much any help

Thanks

[gorkij77]

Mind you, I have the exact same error. But looking at the file: Where's it pulling data from? 

\PrestaShop\PrestaShop\Core\Currency\ExchangeRateProvider
Is this an absolute path?

Because it seems to me it should point to your document root /public_html/src/Adapter/Currency, or am I completely in the wrong here?