The IOTA Foundation said it has resolved a software bug that prevented transactions from confirming on the IOTA network for 15 hours.

According to a GitHub submission from an IOTA developer Sunday night UTC, a bug in the node software created a “corrupt ledger state.”

“There is an edge case where IRI [IOTA Reference Implementation] didn’t account for a transaction that was shared between two distinct bundles. Once it marked it as ‘counted’ in one bundle, it was ignored for the next bundle,” the GitHub post reads.

Users first reported the problem on Sunday, which took IOTA’s engineering team some 15 hours to fix. IOTA founder David Sønstebø said the bug was “minor” and “it’s really no different from periods where the network has been spammed and thus real tx [transactions] slowed down significantly”.

IOTA has asked users running IRI nodes to update to a new software version that patches the bug.

IOTA’s co-founder Dominik Schiener said in an email the issue originated with the “current primary mainnet node software” and had nothing to do with the Coordinator, a special node that’s operated by the Foundation, which is responsible for the final confirmation of transactions on IOTA’s decentralized network, known as the Tangle.

The team has already started to replace it with a new lightweight node, known as Hornet, and said it plans to remove the Coordinator once engineers have fully tested and resolved any possible network problems with an event known as the “Coordicide.”

Following reports on the bug in the network on Sunday, Sønstebø defended the current set-up, arguing this was “precisely why Coordicide takes time, one can’t execute it until all possible kinks have been ironed out.”

Nonetheless, critics have already argued the centralized nature of Tangle curtails performance and makes it vulnerable.

In 2018, blockchain researcher Joseph Rebstock told The Next Web the Coordinator automatically approves the same hash, meaning hackers could steal cryptocurrency from users who reused wallet addresses by repeating transaction data. Sønstebø later denied this was a vulnerability.

In an email Monday, Schiener wrote: “Coordicide is proceeding unchanged, with the first alpha test happening in January.”

The IOTA Foundation designed Tangle as a transaction platform for new internet of things (IoT) initiatives. The Taiwanese capital of Taipei partnered with IOTA in early 2018 to test a new tamper-proof citizen identification system.