I still have a private key from an old Bitcoin wallet (circa 2012), and I have a private key. I downloaded the bitWallet app for iOS, entered my private key there and my wallet with balance and all transactions was displayed. I wanted to transfer bitcoins to my new wallet, but I get the error mandatory-script-verify-flag-failed (Public key is neither compressed or uncompressed)

my secret key is 52 characters long, starts with 5HpH

I am ready to very generously thank anyone who can help me!