Quote from: nejel on August 06, 2017, 07:02:20 AM

Following guide http://docs.electrum.org/en/latest/coldstorage.html I intended to spend bitcoins from paper wallet signing transaction on offline machine. So I created Electrum wallet using given private key. However button Wallet -> Master Public Keys is grey, so I can't obtain PubKey and create a watching-only version on online machine. What is the case?

What kind of Public Key is actually needed? I obtained uncompressed -130 characters and compresed -66 characters from bitaddress.org (offline) but it won't go through.

Electrum-2.9.2
Ubuntu-16.04.2

Master public key is a string of letters that allows the client to generate the public key of any address from a master private key which is generated from a seed. Electrum will not give you any master public key simply because it is not possible to generate one unless you created a new wallet with seed inside of Electrum.

If you wish to create a watch-only wallet, in the setup menu, select "Restore a wallet or import keys" then select standard wallet and paste your Bitcoin address in the box. The procedure for the rest of it will be the same.