Do you have the method to send private keys to SPV electrum please.
Or is the simple solution asking me to wait a bit?
Yes that's it.
Without you I would never have made it.
I will get back to you very quickly.
You are a great community!
1) export the private keys
2) download electrum from electrum.org
3) check electrum's signature (the binary HAS to be signed by ThomasV)
4) when you open electrum, a wizard should appear guiding you trough the process of making a wallet.
4.a) pick a name for your wallet (next)
4.b) chose the option "import Bitcoin addresses or private keys" (next)
4.c) paste the private keys you exported from bitcoin core (next)
4.d) chose a STRONG password (repeat) (next)
4.e) REMOVE the unencrypted file you used to store the exported private keys
4.f) wait a couple of minutes... Electrum will download the block headers... It should take only a couple of minutes tough. But if you exported a long list of private keys, it can take a while... Electrum has to communicate with electrum's nodes and ask for a list of unspent outputs funding each address.
PS.1) Ideally, there is also a fifth step: You have manipulated your wallet.dat quite a bit. You have exported private keys. You have stored your wallet on other media... It's a good idear to make a new, CLEAN wallet, and move all your funds from the wallet containing the imported private keys to a brand new, freshly generated wallet... When creating a new wallet, write down the seed phrase, never store it digitally, but make sure you have a physical, offline copy of said phrase. Don't show the phrase to anybody else, it's private!
PS.2) If you have more than a couple hundred bucks worth of BTC, i'd suggest buying a hardware wallet (ledger and trezor are the most popular brands). If not: learn to make paper wallets in a proper way (completely offline + using the right tools). If not: make an airgapped setup using bitcoin core or electrum using a dedicated pc or a Tails OS usbstick
PS.3) if you opt for a paper wallet or an airgapped setup, do the steps with testnet coins first... Make sure you know how to generate a paper wallet or airgapped setup on the testnet, fund your wallet with testnet BTC, create a transaction spending your funds on the testnet... Only when you are 100% certain about the procedure continue on the main net!
PS.4) It's an old wallet, bitcoin forked quite a bit after unspent outputs funding your addresses were stored on the blockchain. The private keys for these addresses can also be used on several other blockchains to claim a lot of forked coins!!! AFTER you moved all your BTC to a new wallet, you should look into this. BCH/BSV/... are worth considerably less than BTC, but it might still be a good idear to claim and sell them