Hi, I have just bought an SSD (Crucial MX500). After many attempts and various problems along the way I have FINALLY managed to clone successfully using Carbon Copy Cloner. My drive is now bootable from a USB-SATA cable by starting up with option key. So clearly the drive is ok. However, when I install the drive into my mid-2012 Macbook Pro (running Mojave 10.14, 16GB RAM), it won't start. I get a grey screen with alternating Apple logo, question mark folder and no entry sign. I have tried resetting PRAM. When selecting startup disk in recovery mode, I can find and select my new SSD even when it's internal, but it just won't start. I have also tried using a bootable USB to install Mojave on the drive and also downloading it via Internet Recovery but I get the error message 'an internal error occurred while preflighting your volume for APFS conversion'. Restoring from Time Machine or from the old drive mounted externally gives me OSstatus error 1 or 22. I have read dozens of other threads on this and the SATA cable seems to be the most common cause. But going against this for me is the fact that (1) the cable works when I put my old HDD in (i.e. no problems starting up) and (2) I replaced it two weeks ago (this is what got me believing I was competent enough to upgrade the SSD!). I am reluctant to try other cloning methods as I feel I'm at the last hurdle and would love to avoid re-erasing the drive and starting again - having a bootable drive feels like I'm so close to problem solved! Any suggestions greatly appreciated. Thanks so much in advance!