Hi, I have trawled other forums but don't see any solution. Trying to upgrade an early 2011 Macbook Pro from Mountain Lion to Sierra. 100+GB spare on internal drive. (originally I intended to install on an external drive but had no luck after making the drive bootable via the terminal etc etc and following all the install steps but it kept stalling. So i gave up that and decided to just do a clean install on the internal drive after all) Installation looks ok but then just stalls. I let it go overnight so it is definitely stuck. I've performed the following trouble shooting: - booted in Safe mode (doesn't work) - done the PRAM reset thing - reset the SMC - booted in recovery mode: ran first aid on disc tried a clean install (hours later, same result) - shut down & boot up normally I just get the progress bar which slowly fills out & then stalls again So I'm stuck in this stall cycle and don't know what else to do. Any suggestions?