Thanks. I now get to the store, but it gets a 500 Internal Error trying to verify my key. Also, the Purchase link does embed my Arq 4 license key, but in the form, the upgrade license key field is empty, and I have to find it from my old .arqLicense file and paste it. I don't even know if I'm copying the right thing.

They just added a "Retrieve license code" link on the web site below the Arq 4 license code field. I was able to upgrade no problem. FYI.

Same here. Let me know if you figure this out. I'll do the same. I just shot Stefan an email but I'm sure he's inundated at the moment...

Having same key verification problems too. Will try again tomorrow!

Still having the same problem today...