PayPal are in the middle of moving to a new data centre and some merchants will be unable to process transactions during the move. The outage will last approximately an hour beginning on the 18th March at 9am GMT (2am PDT).
The migration won’t impact many PayPal users, but it may affect you if you use Payflow Pro, Payflow Link, Website Payments Pro, Payflow Edition or Website Payments Pro using a Payflow integration Access to reporting applications during the migration will also be interrupted.
There will also be outages to PayPal test and pilot environments on the 17th/18th and the 24th/25th of March. Full details of all PayPal outages and changes scheduled for March, which may affect developers, are available on the PayPal X Developer Network blog.