Warning (2): transliterator_transliterate(): Could not create transliterator with ID "Any-Latin; Latin-ASCII; [\u0080-\u7fff] remove" (transliterator_create: unable to open ICU transliterator with id "Any-Latin; Latin-ASCII; [\u0080-\u7fff] remove": U_INVALID_ID) [CORE/src/Utility/Text.php, line 1073]
Someone here (Minimum PHP version problem) mentioned that not using __ functions would do the job but this is not true.
My config is OK and the standard cakephp home page loads with all specs validated.
I did not forget to add use Cake\Utility\Text; in my controller
Going my way (hope it helps someone …)
In fact, the problem is only in forms.
I could not be aware of it as I could not login.
I managed to log in after re-installing cake 3.3 and once logged in, I could re-activate cake 3.5 and everything works fine except forms.
So I cannot add or edit anything and I cannot log in either.