Does your default wallet have the same addresses as your watch-only wallet?
Because if they aren't the same, there will be no connection between the two and you wont be able to spend the balance of your watch-only wallet.

"I manage(d) to find the private keys"? Means you don't have the private keys or an (offline) standard wallet for that watch-only electrum?
It's impossible to "find" a private key just by having the addresses.

Did you create that wallet yourself?

AFAIK No, if you opened a wallet using electrum, the date/timestamp of the wallet file in the data directory will be updated, including the creation date.

Your wallet and the server (connected node) won't allow it.
If you try to send another 0.5 BTC, your wallet will find another UTXOs to spend, not the already used ones.

There are certain conditions before double-spend can be achieved; like marked as "replaceable" or connection to a miner's node that configured to accept double-spend TXs.
but by using default settings and normal transaction creation procedures, it's not possible to double spend.

It must be because of their website upgrade/update after October 31 or November 1.
Most of the "workaround tricks" by adding something to the URL don't work anymore.

Were those from "beginners and help" board?
'Coz I also got a few unhandled reports there, specially the one obvious copy-paste of a post 8 replies away.
I've indicated the link to the original post, IDK why that particular reports was missed.

For the record, there's no prob with my reports from other threads.

-edit-
B&H board's mod last login was April 04, 2018, 09:24:05 PM.
So only our busy global moderators or admin(s) handle the reports.

Those (bold texts) supports HCP's reply, Bitcoin's addresses starts with either '1', '3' or 'bc1'.
Haven't you followed the last part of my post (#4) above? (Download from electrum.org)

The GUI detected that there's already a "bitcoin" folder in that directory.
There might be something in that folder that makes bitcoin-qt to crash.

Try to delete the bitcoin folder in that partition, then try again. (backup everything if you purposely added/copied that folder).

How about the timezone? Have you set it correctly together with the date and time?
Because it will also reset if your laptop's CMOS battery is dead.

Make sure that it's correct as well.

Blockchain.com's multiple wallets in the settings uses the "account" in the derivation path.

So just a little bit adjustment to BitMaxz' reply is needed to restore your second wallet.
Use: m/44'/0'/1'/0 instead of m/44'/0'/0'/1 which is the external/internal (change) account.

Alternatively, you can contact their support as they are quite buggy after the website upgrade.

This happened during the 2017 bull run when there's a high fee requirement because of too many users sending bitcoins and the alleged transaction spam.
But you won't be able to see those transactions in any blockexplorers anymore since they usually drop it to their mempool and database after a while.

These "conflicting transactions" are more common than you think, it's just because most blockexplorers instantly remove the conflicting tx from their database as soon as they receive the replacement tx. Others are keeping and labeling the transactions "double-spend attempt" (for weeks/months) like blockcypher.

Most of these are legitimate RBF (Replace-by-fee) transaction bumps but others are successful/unsuccessful double-spend attempts.
Or as long as the same input was spent, it will be marked by blockexplorers as "conflicting".
But all of those aren't "uncommon transactions".

This usually happens when you load a wallet file to a lower version of Electrum.
Which might be the case since you've opened an old stored exe file from your past downloads.

Make sure to backup a copy of your current wallet file from the directory above (HCP's post) or wherever directory you stored it
in case there's a corruption happen when you load it to the latest version.

It indicates that you used the wrong backup (SEED), or is it from the receive tab only?
Open the address tab to be sure (View->Show Addresses), receive tab will always show you an unused address.
The correct addresses should be restored unless you made some modification with the derivation path during your wallet creation.

Try to download and install the latest installer/stand-alone version from electrum.org.

It must be their copy of your wallet.aes.json, you can contact their support like others with same problem did, they'll fix it.

But if you wan't to stick with Electrum, create a new wallet with a new SEED.
Blockchain.com may say that they have no access to your unencrypted SEED/prv keys, but it's still better to use Electrum's native SEED.

This looks like the clipboard hijacking virus in action
OP didn't even noticed that the pasted addresses in his reply were identical.

Try to copy any random P2SH (3) address again and if the result is 32fmz1pdmo9XWyMAeNoniaNE94f9ubs6Ae again, you might have a clipboard hijacking virus of a hacker that uses coinpayment merchant account as a diversion (y tho?).
If this was true, you can contact coinpayment's support (link) to hodl the hacker's account by providing evidences.

If not.... uhm.

@Tycek Follow this ^

But if there isn't any problem with the disk, redownloading the blockchain might solve the issue.
You don't have to add any parameter, just delete everything inside blocks and chainstate folder in the data directory to sync from scratch.
You can also add txindex=1 to your bitcoin.conf file from the default data directory and specified data directory for it to work on both Bitcoind/cli and qt.

No, they have the control over your deposit address' private key.
If they said that they wont help you, there no other way.

If that coin's client is identical to Bitcoin Core, you're using the wrong parameter.
It should be addnode= without 's' and can be written in multiple lines if you need to manually add more peers.

If you have added other parameters, please tell us.

That will probably come up as multiple inputs (from Coinbase's Hot wallet) and multiple outputs (to your friend and other users).
Because Coinbase isn't a wallet and they might process withdrawals in batch like other Exchanges do.

IDK if they implemented it already though, 'coz I stopped using their service years ago. (Their statement that mentioned batching: blog.coinbase.com)

You cannot receive? FYI,you can receive bitcoins/alts to your addresses even if your account is offline.
Are you getting the error upon clicking "send" or "request"? It's working at my end.

Before that, please consider lowering your House Edge to at least 2%.
From every thread that discussed "House Edge", freebitcoin had always been mentioned for having a ridiculous HE (Sry for the word).
IMO, it's the major factor why others didn't like the casino part of the site.

BTW, I second UserU's suggestion (Mine Sweeper), but like the one in Stake.

Let me.

• 1. It will be less efficient in terms of transaction fee and if that's how transactions are made, the number of unconfirmed tx in the network will grow exponentially.
• 2. Your client (wallet) decides which input(s) (UTXO: visually, the addresses you see in the "input") to use.
  The commonly used method is: choose the one with the closest balance to the amount being sent, if one isn't enough, the wallet will use two or more.
  Some clients are choosing random UTXO(s) for privacy purposes.

The cost and the total available hardware.
The cost might not be a huge problem for a state but after the attack, what will they do to those ASICs that they've used for the attack?
But before that, where will they get the necessary hardware to gain 51%+ of the current network hashrate? Produce their own?

(They will be needing more than half of the current hashrate since their own hash power will be added to the total).

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Forcing the Pools (not the miners) is more effective and cheaper than than "setting up their own farm" but a lot harder to pull off.