If you get the message that your Palemoon browser is out of date, then follow these steps to fix the issue:
Implement a workaround in Pale Moon while PayPal takes their (often sweet) time to address this issue:
In your address bar, type about:config and press enter
This opens up the advanced preferences editor
In the list you see, right-click and select "New" and then "String" to create a new preference value
For the new preference name, use general.useragent.override.paypal.com
As value, use Mozilla/5.0 (Windows NT 6.1; WOW64; rv:27.0) Gecko/20100101 Firefox/27.0
