If this error occurs when transferring data from PlayStation®4 to PlayStation®5, please try the following steps:
If your PS4 and PS5 are connected to the network wirelessly, try transferring data by connecting each console to the network using a wired connection or by connecting both consoles directly with an ethernet cable.
Turn off your router and wait at least 5 minutes, then restart it.
Try transferring data again by going to Setting > System > System Software > Data Transfer
If you only want to transfer save data, please try transferring via another storage medium such as online storage or USB storage device as an alternative method.
Please note the following:
Do not use the Network Test feature while Background Data Transfer is in progress.
Do not manually turn PS5 into Rest Mode while Background Data Transfer is in progress.