You can no longer create a new PSN account directly on the PS Vita console. New accounts must be created using a web browser.
Connect your Vita to a PC running the Content Manager Assistant and select Update by Connecting to a PC . ps vita 374 firmware
For PlayStation TV users, you can update via a USB drive. Create a folder named PSVITA on the drive, then a subfolder named UPDATE , and place the PSVUPDAT.PUP file inside. Impact on Homebrew and Jailbreaking You can no longer create a new PSN
Following this update and the concurrent PS3 4.89 update, users can no longer transfer games or content directly between a PS3 and a PS Vita via USB or Wi-Fi due to the new authentication requirements. How to Update Your PS Vita For PlayStation TV users, you can update via a USB drive