Topic: Invalid OTP when sending >.2 amounts of BTC (Read 138 times)

A couple of possible reasons...

1. Network issues. OTPs are time sensitive... The Google Authenticator codes are only valid for 30 seconds. If there are network issues, the code may have expired by the time that TrustedCoin attempts to validate it.

2. Authenticator out of sync. Again, because GAuth OTP codes are time sensitive, if the time on your device is out of sync with the Google servers, it's possible that the 30sec window is actually shorter and you're just missing it every now and then.

The GAuth app you use should provide a "sync" option... For example, if you use "Google Authenticator" app, you can follow the instructions from Poloniex here to try and resync your device: https://poloniex.freshdesk.com/support/solutions/articles/1000227645-my-two-factor-codes-aren-t-working-incorrect-code-errors-

Personally, I use "Authenticator Plus" and it has a "Sync with Google" option in "Settings -> Other".

3. TrustedCoin are having technical issues. Try contacting them if syncing your app doesn't help. They have a contact form here: https://api.trustedcoin.com/#/contact-us

4. If you have a LOT of inputs from a LOT of different addresses, it's possible that the time it takes to sign the transaction is longer than the validity period of the OTP... So by the time Electrum has signed the transaction and transmitted to TrustedCoin, the OTP flags as invalid.

You'd need to preview the transaction and see how many inputs are being used for the transaction when it fails.

The only way I can think of getting around this would be to temporarily restore a "2fa disabled" version of the wallet, so you can self-sign without 2FA... Send ALL your coins back to yourself to consolidate all the inputs into one UTXO and then delete that "2fa-disabled" wallet and go back to using the original 2fa one.

What kind of OTP are you using?
Timebased one time passwords (TOTP) or HMAC-based one time passwords (HOTP) ?

When using TOTP you have to make sure your mobile phone has the correct date/time set.
An offset of 30 seconds could lead to ~50% of codes you enter to be invalid.

With HOTP the date doesn't play a role. However all of your requests should work this way.


The amount however shouldn't play a role at all.
If you are using HOTP method or are sure your system has the correct date set, you might be facing a bug.

Sure you have the funds, if not, you wont be able to (2/3) sign the transaction in the first place.
That 0.5BTC is BTC right? not 0.5mBTC/uBTC?

• Are you sure that your Smartphone with Google Authenticator is online and date&time synced?
• Could be a fake, Electrum's only official site is electrum.org, make sure that you've downloaded yours from this site. (there are fake copies of the site containing malwares)

It you want, you can disable 2FA service for a hassle-free sending transactions (but less secure).
Here are the Steps, by HCP.

3.1.3

this is very very weird, I sent .5, it worked. But I try .5 again, doesn't work. I try .2, works. Try .2 again, doesn't work- invalid OTP again.

It seems like the less and less I send, it'll work but this is going to not work for me. I have no idea what's going on. send help

This is weird, "invalid OTP" often occurs when your Google Authenticator Phone isn't synchronized or has an invalid date and time.
With the amount as the culprit, it could be a bug.

What's your Electrum's version?

I have a 2fa wallet, when I sent less than like .5 BTC, it'll work fast and send. When I try higher amounts, it'll get stuck on signing transaction for two minutes then give error invalid OTP. Why?