Problem:
The following error occurred while saving a product from Magento 2 admin:
Invalid Form Key. Please refresh the page.
Cause:
The cause of this error is related to the max_input_vars (Maximum Input Variables) directive in the PHP settings.
The max_input_vars directive value is the maximum number of variables that can be used for a single function.
By default, the value of max_input_vars is 1000.
Solution:
The value of max_input_vars should be increased to solve the error.
To increase the max_input_vars value, we need to edit the php.ini file.
You can find the path of the php.ini file with the following command:
php -i | grep php.ini
Output:
Configuration File (php.ini) Path => /usr/local/php5/lib
Loaded Configuration File => /usr/local/php5/lib/php.ini
Open php.ini file and increase the value of max_input_vars:
; How many GET/POST/COOKIE input variables may be accepted
max_input_vars = 5000
Save the php.ini file and then restart your webserver.
If you are using Apache WebServer, then you can restart it with the following command:
Mac OS:
sudo /usr/sbin/apachectl restart
Linux (Debian/Ubuntu):
sudo /etc/init.d/apache2 restart
//OR
sudo service apache2 restart
Linux (CentOS):
sudo /sbin/service httpd restart
//OR
sudo systemctl restart httpd.service
Hope this helps. Thanks.