EXM CD RedirectUrlPage return Null

Question

I've set up a Sitecore 9 instance in Scaled-Multisite Environment. I sent an email campaign through the EXM but I got an error when I tried to click on the link inside the body email.

Error in frontend Error in log

I got this error when I tried to click url with this format <CD-URL>/sitecore modules/Web/EXM/RedirectUrlPage.aspx?ec_eq=XX

But when I tried to access the url with <CM-URL> it's redirected properly.

Things I've tried

• Check on CD and CM exm.master connectionString - ensuring it's same and can connect.
• Check on CD and CM EXM.CryptographicKey and EXM.AuthenticationKey - ensuring it's same value.
• Create specific hostname mapping under /sitecore/system/Settings/Email/System/Hostname Mappings with Original Url : <CM-URL> and Public Url : <CD-URL>
• Ensure Base Url field in Email Manager Root is <CD URL>

Answer 1

Please also check your settings on the manager Root:

They are used how the links in the mails are generated.

Base Url should point to your live-url, Preview base URL should point to your CM-Instance.

Best regards Dirk

Answer 2

My assumption would be tha there is an item or a template change, which is not published to CD Server. It works on CM and you get a nullreference exception on CD Server.