I have created a Login flow for users to prevent them from having Concurrent login sessions using below URL:
https://developer.salesforce.com/page/Concurrent-Sessions
I'm able to successfully test it in my Developer edition org with Summer '17. 
But in a sandbox which is having Winter '18 edition, upon logging with only one active session - I'm receiving below message and not able to navigate to anywhere else except logging out :
'Your Flow Finished' 


Also, found this known error link but the workaroud didn't help either:
https://success.salesforce.com/issues_view?id=a1p300000008XZ5AAM&title=your-flow-finished-screen-should-not-leave-users-stuck-in-the-flow
 

I have created a Login flow for users to prevent them from having Concurrent login sessions using below URL:
https://developer.salesforce.com/page/Concurrent-Sessions
I'm able to successfully test it in my Developer edition org with Summer '17. 
But in a sandbox which is having Winter '18 edition, upon logging with only one active session - I'm receiving below message and not able to navigate to anywhere else except logging out :
'Your Flow Finished' 


Also, found this known error link but the workaroud didn't help either:
https://success.salesforce.com/issues_view?id=a1p300000008XZ5AAM&title=your-flow-finished-screen-should-not-leave-users-stuck-in-the-flow
 

https://workbench.developerforce.com/ is returning an error 


Error: This site can’t be reached
workbench.developerforce.com’s server DNS address could not be found.

Anyone else having issues accessing the workbench site?

https://workbench.developerforce.com/

Create an Apex trigger for Account that matches Shipping Address Postal Code with Billing Address Postal Code based on a custom field

I used the code below and am getting this error... "Challenge Not yet complete... here's what's wrong: 
Setting 'Match_Billing_Address__c' to true did not update the records as expected." I have no other triggers or validation rules activated. any help would be much appreciated. Thanks in advance

trigger AccountAddressTrigger on Account (before insert,before update) {


List<Account> acclst=new List<Account>();
  for(account a:trigger.new){
    if(a.Match_Billing_Address__c==true && a.BillingPostalCode!=null){
    a.ShippingPostalCode=a.BillingPostalCode;
        
    }

}
}