Coinone won an appeal to force five of customers to return bitcoin (BTC) they managed to double withdraw from the South Korean crypto exchange over a glitch in 2018.

According to local media, the Seoul Western District Court’s second civil division said the traders benefited from “unjust enrichment” because the exchange had already completed the first withdrawal on-chain before its server restored their balances.

The mix-up began when Coinone’s software flagged slow confirmations from the Bitcoin network as failed transactions, and automatically topped up users’ accounts even after the withdrawals were properly processed. The traders then withdrew same coins again.

The Bitcoin network experienced significant congestion back around that time as transaction volumes skyrocketed, in the culmination of a years-long scaling debate that had led to the Bitcoin Cash (BCH) hard fork a year earlier.

At the time, the average transaction fee on the Bitcoin network reached a then-record $55, while the memory pool, a sort of “waiting room for transactions,” grew to 250,000 unconfirmed transactions.

A lower court initially blamed Coinone’s own servers and ordered the payment of only partial damages. On appeal, judges called the network delay an outside event, said the platform need not shoulder the loss and told the users to repay the funds.

Coinone has faced controversy in the past. In a separate trial in 2023, former employees admitted receiving as much as 2 billion won (around $1.46 million) to list tokens.