Need Help Accessing Old BTC Wallet

I dug around today and found an encrypted file in dropbox. It has a wallet ID from blockchain.info and a password. I know I had some BTC in that wallet ages ago. There's also a 20-word mnemonic in the file... but when I try to recover it on blockchain.com, it doesn't work and the mnemonic seems too long. The password is fine, but then it asks for a second password that I totally forgot... Tried all my passwords from 2012-2013 but nothing. What can I do? Any thoughts on what kind of wallet uses a 20-word mnemonic?

Without that second password, you're stuck. You’ll need your "wallet.aes.json" for BTCRecover to brute force it, but I doubt those tools work for the newer version. Good luck with that, tho. I guess that recovery phrase isn’t BIP39 compatible since you found it in the same backup. The restore page you tried is probably meant for the 12-word BIP39 phrases. Have you thought about contacting their support? It might help.