Hi guys, I know a lot of people have been having troubles with bootcamp after installing High Sierra, not being able to install Windows, or not being able to boot into the mac partition when they were using the windows partition using bootcamp, but my situation is a bit different, I think. I have a Mac Pro 2010, I used to have a Mac Pro 2009, I simply took my SSD out (I had Sierra and a fully working dual boot situation with Sierra and Windows 7 using bootcamp) and put it in my Mac Pro 2010. The « new » Mac Pro had a PCIe SSD already inside that wasn’t seen by Sierra so I had to upgrade to High Sierra. And here started all my troubles. After the upgrade, I’m not able to boot into Windows anymore. On top of that, of course, to complicate matters, I have a NVIDIA graphic card, which is unflashed, and prevents me from using a bootcamp manager. It was never a problem until then. Anyway, seeing that booting into windows from bootcamp (selecting my windows partition to restart the system) let to infos about my graphic card, like usual, and then a black screen with a blinking cursor on the top left of the screen and nothing happening, I felt something went wrong. I booted again, same thing. Because I’m lazy AF, I took out the SSD and attached it to my Mac mini and started the Mac mini with alt, to be able to start on the Mac Pro system from there. I booted into the mac partition and there, selected restart as mac. Still, I got the black screen when I put the SSD back into the Mac Pro. Laziness has its limits so I switched to the original old graphic card to see what was wrong. Still not mean to get to the drives. After resetting PRAM, I finally got to the boot manager, and was able to boot into mac. From there, I restarted into the PC mode, to see what I could do. Same thing with the black screen and blinking cursor. Obviously, my windows partition is still there, I can see it, with all the files names, windows, program files, etc. I don’t think the MBR was tampered with in any way. I haven’t tried booting to windows while on the Mac mini, that’s one thing I could still try. But everytime I tried booting into the windows partition from the bootcamp manager, it ****ed my computer to the point that I had to reset the PRAM to get the startup manager back. What do you think went wrong? I could, of course, reinstall windows, I don’t have that many things there, I’ll miss my Tomb Raider 2018, but it was a brand new windows install so I don’t really care, but the fact that I’m getting this weird blinking cursor tells me it’s a whole other level of trouble. And from what I read, with the new file system, even if I get windows working, I won’t be able to get back to my Mac partition from there because windows won’t be able to see it. I can obviously get rid of the PCIe SSD and sell it, it’s a 500Go SSD... But if there’s a simple solution where I can keep everything inside the computer and make it work, I’d rather try it first. Thanks! --- Post Merged, May 15, 2019 --- Here's a screenshot of my diskutil list. I feel there's something weird happening here... My "bootdrive" is my mac partition, "bootcamp" is obviously my windows partition. But Apple_APFS Container Disk4 is also my mac partition (bootdrive). I don't know why there's a "synthesized" disk listed, that's the first time I see something like that. I saw somewhere on the forum the "bless" method for the windows partition but I have no idea how to apply it here with this weird mix up of disks. My PCIe disk is appearing as external.