From Magnum`s Telegram post:
today we are forced to inform you that in 20 days Magnum Wallet will be suspended.
It was a difficult year and a difficult decision for us.
We remind you that Magnum Wallet is a non-custodial wallet. Magnum Wallet doesn’t have access to and doesn’t store your personal data, and only provides you with viewing data from the blockchain. You can use any other cryptocurrency wallets to access the blockchain through your private keys.
We also remind you that it is you who should keep your private keys. We regularly suggest that you save them from Magnum Wallet. If you haven’t done this yet or don’t remember the place where you store your private keys, then below are instructions on how to do it right now.
We highly recommend doing this soon.
Magnum Wallet will be suspended on the 30-th of November at 6pm GMT.
Thank you for using our product.
*For downloading your Private keys, *
1) Click a link "Download Private Keys " in the Top of the web site
2) Copy or Save Private Keys"
We’ll check their key derivation procedure, so then it will be possible to import keys into the node at least. Maybe we’ll do some special migration website, depends on how many users will have their coins associated with Magnum keys after Nov, 30th.
Please use wallet in-built in full node, Yoroi or Coinbarn https://ergoplatform.org/en/wallets/