How to Fix Invalid Form Key Error
If you get the dreaded “Invalid form key” error while logging in or working in the admin, something is wrong with your setup.
Since version 126.96.36.199 (and patch SUPEE-6788), Magento requires a secret form token to prevent XSRF attacks. Here are some solutions. For these solutions we assume that you have Magerun installed, because on Hypernode it is installed by default.
PHP choking on too many form values?
Create a file
/data/web/public/.user.ini with this line:
max_input_vars = 75000
Last resort: disable admin form key
If you are locked out of your admin panel, you could use this as last resort:
magerun config:set admin/security/use_form_key 0 magerun cache:flush
However, this should only be used as a temporary measure, so you can figure out what is wrong with your setup.
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