Why does PayPal keep rejecting my credit or debit card?

If PayPal shows "The card you entered cannot be used for this payment", it may be because: the card is linked to a PayPal account you're not logged into; that linked account has been closed; the card is linked but not confirmed; you've exceeded your PayPal card limit; your email triggered a PayPal security flag; or browser cookies are disabled — try clearing or enabling cookies.