NHS system failure means thousands unable to see GPs
Tens of thousands of people might not have been able to book GP appointments on Thursday after a power failure affected systems.
About 124 surgeries using a system owned by NHS Wales experienced technical issues at 08:00 GMT.
It meant practices were not able to manage appointments for patients and access medical records.
Digital Health and Care Wales said the issue had been resolved and is working to bring all systems back online.
One practice manager said the problem will cause an additional backlog to an already busy service.
"The five hours of downtime has significantly impacted those general practices affected today, in what is already a very busy time of year, with winter pressures and significant increases in demand for GP appointments," said Gareth Thomas of the Institute of General Practice Management Wales.
"Ultimately, a number of practices would have reverted to an emergency only systems for patient safety reasons with any planned appointments having to be cancelled and rearranged.
"It means that significant rework will need to be managed over the coming days."
His surgery, in Barry in the Vale of Glamorgan, was back up and running just after 13:00 but he said others were still being affected.
In 2018, a major IT failure affected patients attending hospitals and more than half of Welsh GP's surgeries.