Stablecoin issuer Tether accidentally created $5 billion-worth of its USDT stablecoin at the weekend, before promptly destroying them again.

The mess-up occurred when the company was helping cryptocurrency exchange Poloniex conduct a chain swap, moving tethers from the Omni to the Tron blockchains, according to Tether CTO Paolo Ardoino.

Ardoino explained in a tweet on Saturday:

“Tether is issued on multiple chains (Omni, ETH, ..) When @bitfinex receives too many deposits for Tether-Omni and then users want to withdraw Tether-ETH, @bitfinex sends back to @Tether_to the Omni ones and gets back the same amount in ETH.”

In another post, he explained that the error had occurred because there had “been an issue with the token decimals” when when preparing the issuance for the swap.

Poloniex, which is owned by crypto finance firm Circle, confirmed the error in its own tweet, adding, “An incorrect amount of USDT was accidentally minted, and this has since been resolved to the intended value.”

The mistakenly issued coins have now been destroyed, or “burned,” with Ardoino providing links to the burn transactions here (4.5 billion USDT) and here (500 million USDT).

Ardoino (kind of) apologized for the error in yet another tweet, saying:

“Unfortunately we have to play with different toolchains across multiple [blockchains] and sometimes issues happen. We’re working anyway to prevent this from happening in the future.”

Minting dollars illustration via Shutterstock

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