Magento 2
v. 2.2.1
This module fix the date format bug ( Invalid input datetime format of value ).
When the format is Day, Month and Year. dd\mm\YY .

Installing:

Simply paste the FernandoFauth folder on (magento root)/app/code
After installing the module upgrade your store.

bin/magento setup:upgrade

Check if your cache is clean.
Check if the Interface Locale is Português (Brasil) / português (Brasil) or other language that use the dd\mm\YY format
Certify if you using developer or production mode.

If using production mode, you need recomplie the store code.

Follow this steps
bin/magento setup:upgrade

bin/magento indexer:reindex

bin/magento deploy:mode:set production -s

bin/magento setup:di:compile (Here was the secret, to run the di:compile after production)

bin/magento setup:static-content:deploy (lang_code) [ ex: bin/magento setup:static-content:deploy pt_BR]

Other thing you can do is check your folder permissions.