Hello,
Since last friday 19.03.2021 my website is unable to complete any orders.
The customers can perform any changes until it reach to the point they need to complete the order (Cash on delivery). Once they place the order they receive this message (with debug mode on)
"UndefinedMethodException in ps_emailalerts.php line 552:Attempted to call an undefined method named "getLocale" of class "Language".
Did you mean to call "getLocaleByIso"?"
My assumption is that the issue is comming from the language, translation. Maybe something is connected to this as I "play" with those options ... adding or deleting language (en only as the site is only for romanian market)
I am unable to understand what I have to do to revert to the old state 
I also install a new Cash on delivery module,and I have the same behavior like the original one (switched back to the old one), reseting did not solve the issue, is just the same.
The orders are not finalized ...
Additional info:
Prestashop 1.7.2.4
PHP was 5.6 now 7.1.33
I REALLY appreciate any help.
I can provide any details might be usefull to find a sollution.
Catalin