My LR5.7 on Windows 7 crashed. I tried many things and had to download a new version (5.7.1). It doesn't recognize my activation code anymore. Tried each code I had since LR1. What to do?
One possible cause is that you downloaded the Creative Cloud version of Lightroom, which doesn't accept your serial numbers; instead you should download the stand-alone version (which does accept serial numbers) from Product updates
Retrieving data ...