The Australian Securities Exchange (ASX) said it would delay an overhaul of its stock trading software for up to 20 months, citing scalability and resiliency issues.

The delay to the end of 2024, among several, brings ASX Ltd’s plan to modernize its Clearing House Electronic Subregister System (CHESS) stock clearing software to almost a decade.

CHESS software enables ASX’s ledger to handle trade settlement, and the exchange has been working since 2017 to replace it with blockchain technology in a bid to reduce costs for customers.

ASX, which has been plagued with several software issues, said it would hire Accenture to provide an independent review of the new CHESS app. Accenture’s review will identify actions for ASX to communicate a revised timeline to complete the project.

The exchange operator and its application software provider, Digital Asset, realized that the application needed more work than expected.

Helen Lofthouse, Managing Director and CEO of ASX, said, “CHESS is a critical system and we need to have great confidence in the timeline to deliver the new CHESS safely. I apologize for the uncertainty and thank them for their close and constructive work with us on this important project.

In a joint statement, Reserve Bank of Australia Governor Philip Lowe and Australian Securities and Investments Commission (ASIC) Chairman Joseph Longo expressed disappointment at the further delay.