According to electrum, you are trying to spend inputs you don't have the corresponding private key of.

What version of electrum are you using ?
And how did you create the transaction ? What were your actual steps ?

in short you are trying to spend bitcoins that you don't own.

in other words you are spending a transaction output that doesn't belong to your key. maybe that transaction wasn't confirmed, or double spent and became invalid,... i can't tell without having more information but one thing is for sure, your transaction that you are trying to broadcast is invalid that is why it is being rejected.

go to your wallet, in history tab, and see if you can see any transaction that is marked unconfirmed or local. and see if you can find a transaction that starts with 426b28... it seems like this is the tx you are trying to spend and fail to do so.

no, you just upgrade and the new version will open the old wallet and you will be good to go.

but as i said it is a good idea to keep a backup just in case something went wrong. in your case make a copy of your wallet file and write down your private key(s) on a paper (eg. printing them in which case make sure your printer is not storing them in its memory).
your wallet file is here: %appdata%\Electrum\wallets
and your private key can be found either by right clicking on each address in your "Addresses" tab and selecting private key then entering your password. or you can go to "Wallet > Private keys > export" from the menu and export all your keys.

is it really "always" or is it just taking more time? what is happening in the background is that you are downloading a file that is more than 40 MB in size and it can take a while depending on your internet speed. you can find the file here on windows: %appdata%\Electrum it is called blockchain_headers

as for upgrade, you are not switching wallets from one implementation to another like what you did with Multibit to Electrum. you are just getting a new version of the same implementation which is from 2.8.2 to 3.2.3
the only thing you need to do in this case is to have your SEED backed up by writing it down on a piece of paper. sometimes it is best if you make a copy of your wallet file too before making the upgrade but SEED is more than enough.
the process is downloading the new version installer from the official website, then verifying its signature, and if it was valid then simply install the new version by double clicking on the installer (for windows, in Linux simply replace the old files with the new ones that you get by extracting the tarball).


you don't need to import private keys for upgrading but just so you know, it is possible to do it. it's just that Electrum is preventing you from importing a private key in an HD wallet (a wallet that has seed) to prevent you from having 1 key among other keys that can not be recovered from seed while the rest can! so it forces you to create a separate new wallet and import that 1 key there so it is obvious that this key is not recovered by your HD wallet seed.

Update your Electrum to the latest version.

AFAIK there are synchronization issues for versions below 2.9.3;

Creating a wallet using a public key will generate a watching wallet. Basically, it means you can see the deposits and withdrawals, but you can't make any withstands.

To withdraw or "spend" coins you must have a private key. So if you export your private key and import it you will definitely be able to spend any coins in that address.

As for the backup, by default, Electrum will generate what is called a "Hierarchically Deterministic" or HD wallet. This is just a fancy way of saying that given a set starting point, it can regenerate the same addresses/keys all the time. As opposed to  older wallets like MB Classic that just regenerates random addresses.

The set starting point is known as the "seed" or "wallet words". This means you just need to write down your seed and keep it somewhere safe and you'll be able to restore your whole wallet just using the seed.

Because HD wallets generate a set list of addresses/keys, generally,  you cannot import private keys. You need to "sweep" the key which effectively creates a transaction that sends from your old address to an address in your new wallet.

Electrum will allow you to create an "old style" private key only wallet that you can import into, but then you won't have a seed to be able to backup your wallet with. You'll need to make backups of your wallet file (and/or the keys)...

So, the best plan is create an HD wallet and then sweep the private key(s)... You'll have the security of a seed based wallet.

Neither. There is one private key per address that is contained in your wallet.

If you are using multibit classic there's instructions explaining how to switch to electrum without moving your coins at this link.

https://bitcointalk.org/index.php?topic=1922317.msg19181835#msg19181835

Without the transactionID we can't really help. Post it here and we can investigate further.

What I can say is that you're using MultiBit Classic, which is very old and outdated... the fees it would have used would have been VERY low by today's standards, so I'm not surprised your transaction is stuck.

For low fee help, put your transaction ID in here: http://www.mocacinno.com/page/feechecker and you will get a number of options.

What do you mean ? The game is happening right now, and the score is already 1-2 which means a win for both the tips. All 3 tips have been wins today.