TL; DR: I am trialling parallels and I went through a full weekend of resolving hard disk corruption and reinstalls of windows due to parallels not handling things very well. Despite this, I am not quite ready to abandon parallels, but would very much like to see some solutions to known problems before I part with money and buy it. The full story: I'm an old parallels user from back in the days of 2.0. I use bootcamp and was getting fed up of switching between operating systems, so I thought I'd give parallels a go so I downloaded the trial of version 13. Everything went smoothly at first and I was ready to purchase. I started up parallels on Saturday morning, and windows 10 started to do an update. Everything looked fine, until I received a warning about windows having attempted to alter the MBR. Apparently the attempt was blocked (much like the problem described and unanswered here: https://forum.parallels.com/threads/mac-os-x-prevents-write-to-mbr-after-win-10-update.342784/). Windows then told me that it was going to roll back the update. However, windows ended up in an endless cycle of never being able to start up. Fearing the worst, I tried to restart into bootcamp with the same results. My windows partition had been lost. Damn. I then tried to boot into MacOS, wipe the bootcamp partition and restart. I restarted and discovered that my MacOS partition was gone. I tried disk utilities, disk recovery tools, nothing could fix it. My entire hard was gone. I repartition the hard disk, reinstall macOS, reinstall bootcamp, activate windows, and reinstall parallels. This time, I make sure that all the updating is done in bootcamp. Now, however, parallels tells me that windows is not activated (http://kb.parallels.com/uk/9703 and http://kb.parallels.com/uk/114051). I follow the information in those KB articles, but nothing works. I finally find this guide: https://forum.parallels.com/threads/unable-to-access-windows-activation-servers.342840/ and follow the information there. I manage to remove the activation, but I cannot reapply it to windows under parallels. I call Microsoft and am told that the advice from parallels is wrong. They try everything to fix the situation, but cannot. Having now removed the activation, I must now completely reinstall windows. Except that since I upgraded from windows 7, I must reinstall windows 7 and reupgrade to windows 10. Another four hours lost. I do this (facing the same activation problem) and get back in touch with Microsoft. They treat the situation as if I had a new motherboard installed and give me a licence key. This is what I was asked to do in http://kb.parallels.com/uk/9703 and http://kb.parallels.com/uk/114051 so I am hopeful this will fix the problem. After 20 minutes of messing around, they finally manage to activate windows in parallels hurray! I restart into bootcamp, to discover that windows is now no longer active, because my hardware configuration had changed. If, as stated by parallels support, the hardware is treated as being different when bootcamp is virtualised, then the hardware is always going to have changed when I boot between bootcamp and parallels. Since you can't have windows activated twice, it seems that this is an unsolvable problems. Four hours of reinstalls later, it's Monday morning. I've lost my weekend, I've lost all my files, but I finally have bootcamp and macOS reinstalled, and bootcamp is activated (but not parallels). Somehow, despite all of this, I'm not quite ready to abandon parallels altogether. I would, however, quite like to see a solution to the activation problem that works.