Signs are beginning to show ethereum's next big upgrade might not be as smooth as expected.

At press time, the parity client, maintained by U.K.-based Parity Technologies, and which supports roughly 25 percent of all ethereum nodes, has yet to release software that includes the protocol changes needed for the shift. The delays come at a time when most other major versions of the software have already published their releases ahead of Sunday's likely fork.

But while not yet cause for alarm, the wait could foreshadow issues. That's because, in order for a successful hard fork to occur on ethereum, all nodes must update their software with a release that contains the block number as well as any agreed protocols.

When the block number is reached, these upgrades are automatically triggered across the network – unless there's a problem with the software.

Notably, Parity has released two Byzantium-ready releases in the past week, however, both were found to contain a "consensus bug," meaning that Parity nodes would not have been able to communicate with the remaining network, causing the blockchain to split.

At present, Parity developers are working hard to get the release out on time.

According to Ether Nodes, 17% of Parity clients are running faulty Byzantium software, while 80% have yet to upgrade at all. If the release isn't ready on time, it could release some very sticky complications down the line.

Speaking to CoinDesk, unofficial release manager for Byzantium Hudson Jameson said the new Parity will be "released very soon I'm told."

Old clocks via Shutterstock