M1 MacBook Air: Migration Assistant mah.. TL;DR: Migration assistant is for sure handy but not fully reliable I have been thinking of replacing my 2013 laptops whole year 2020. Although 2013 MBA was (still is) enough for 90% of my work on the computer, I’ve felt small stress by very tiny hiccups such as slowness or non-smoothness of heavy web programs. Also battery life after Catalina is not great. Under this pandemic, I do not go out and work on the laptop but I do walk in my home and work here and there. so the battery is still quite important for me. As new M1 Macs are quite reasonable even if I compare with some Windows Laptops which satisfy my requirements for new laptop. So finally I bought one. Anyways, I started initial setup and set HDD which timemachine backup exists. the procedure is quite similar to what I’ve done when I replaced SSD of my 2013 Air. So no hesitation, choose the latest timemachine backup. This makes my new Air to be almost identical to the old one. It is in my opinion, very big advantage of Mac OS against Windows. So I wait and everything just works, right ?…..Wrong. The Air indicate that the recovery takes for 23 hours. It is quite impossible as the data is around 250GB. Although it is USB 3.1, it should not be that slow. Indeed, I had an idea. I used small commector (USB-C-USB-A)which I got from my wife’s Samsun S10 to connect USB-A backup HDD. I thought it might have not been for hispeed transfer. So I cancalled the migration. That might have been the big mistake. I connected the HDD to the Air via TB3 hub. and restareted the migration. Failed. It had sudden death (shutdown without warnings) and again, failed. I had a bad feeling at that point so I decided to setup first without data migration. This should be work, right ? Wrong again. I manually backed-up all necessary data from my old Air to HDD, setup the new Air and tried to copy all data. [Not enough storage, cannot finish the job] …..what ? This is the brandnew machine with no data. Strage manager told me that there’s only 80GB of available storage and nearly 400GB “other” data occupied the SSD. What on earth is it ? I googled it but I cound not find a nice solution. So I went the next step. I now went on recovery option by pressing powerbutton long. tried to restore from the very first snapshop of the machine. This must have restored the state of the initial power-on. I might have been able to fully initialise the machine but I saw some reported it could’ve made machine totally brick. So I avoided it. After recovery from the snapshot, it looked fine and storage was also okay. So I continued with copy the data from HDD and installed applicaitons manually. then I tried to open Safari. [You do not have permission to open the application “Safari”] so you telling me I have no control on my computer ? wait computer, what are you saying now ? I am the owner and has admin right. I don’t even open the ordinary applications ????? I found several other problems mainly permissions such as unable to save the data from Davinci Resolve or unable to change some system configuration from system preference. Finally, the correct answer; Re-install OS. It made everything be okay…… well. I never expected that in 2020 Apple computer is “It just does NOT work”. P.S. When you cannot open Safari, you cannnot install other browser such as Chrome of Edge as they are not in App store. Fortunatelly there’s one brouwser application called Maxthon can be installed via App store. jus in case if you need it….