Q:

Can't log in to PayPal sandbox account

I am trying to log into a PayPal sandbox account for testing purposes.  But, I am continually met with the same error:
"We're sorry, something went wrong during sandbox account linking.  Please try again." 
Here are the steps to replicate the issue (happens in FireFox and Chrome). 

Login to developer.paypal.com using live PayPal account credentials. 
Navigate to Dashboard>>Sandbox Accounts
Click Create Account button. 
Create account using any variety of options, e.g. personal, business account.  New account is created. 
Tick the checkbox next to new account listing. 
Click link "Click here and provide credentials of your sandbox account." 
Fill in login form using sandbox account credentials. 
Click agree to terms button. 
Redirected back to Sandbox Account page with "We're sorry" error. 

This happens over and over with newly created accounts and existing sandbox accounts.  I've tried changing passwords and settings for the accounts.  I know a few years ago Chrome had a hard time juggling different cookies and sessions when logging in and out of sandbox accounts.  So, I've also tried using multiple different browsers.  Nothing seems to alleviate the issue.  
Also, I thought maybe this issue was a temporary PayPal sandbox glitch, but I've been experiencing it for over a week. 

A:

Okay, I spoke with PayPal's technical support.  It turns out that they are having some internal issues with the sandbox at the moment.  If anyone else is having an issue with logging into one of their sandbox test accounts do the following:

Go back to the Sandbox Test Accounts page where it list all your test accounts. 
Click on the email address of any sandbox account.  There will be a drop down of "Profile" & "Notification". 
Click on Profile and you shall see an iframe with a few tabs.  You would be able to see the change password, change password. 
Use this url to login to your sandbox account.  https://www.sandbox.paypal.com/home

The key here is step 4.  Don't click on the provided link labeled "Click here and provide credentials of your sandbox account."  Copy and past the above URL into your browser instead.