I'm running LR 5 and just purchased an upgrade to 6. I wanted to backup my catalog before installing the upgrade but get the above message when I start LR5. I have a Mac running Yosemite.
I downloaded and installed the Application Manager but when LR starts up it wants a serial number. My receipt from Adobe only shows an order number and order date. When I log into my Adobe account, there is no record of my LR5 upgrade purchase.
How do I solve this problem?
Update - finally found the SN for the old LR version. Problem solved.