Although I have read some possible ways to remedy this, I have also read other reports of those who cannot fix the issue, and their MacBook becomes worthless. As I'm sure most of you know this update BRICKED (ruined) some of these models. I did not test other parts of the system or programs, there may have been other issues, but I wasn't going to put up with the App Store issue. Had to revert back to Catalina and leave my computer on for over a week to repopulate the people section of photos (I have 40,000 photos) amongst some other nonsense time consuming issues. I researched and tried the fixes I could find with no luck. The App Store would not load after the upgrade.

I did so reluctantly after reading success from others, my system was fine and stable but I wanted some of the new features. I personally would not upgrade to Big Sur (again). I have a nearly new MacBook Pro (Retina, 15-inch, Late 2013 / 2.6 GHz Quad-Core Intel Core i7 / 16 GB 1600 MHz DDR3). I love Best Buy for helping me with every large purchase, from Computers and Dishwashers to Monitors (TVs) and Microwaves. I'm not sure about some rules here but when it comes to tech these days (and home appliances) I've been doing the Best Buy pay overtime plans. Summary, don't update to Big Sur unless Apple makes you and hopefully by then your finances will have settled. Their prevention was almost like seeing actor Wayne Knight in his Jurassic Park role on the computer screens waving his little finger at me. Apple even prevented me from using Safari. Ultimately it met its maker when I could no longer update individual pieces. I did everything I could to make sure I squeezed every drop of possible usage even installing the max Ram (which was not much.) My first big desktop Mac from that time period is still sitting on the floor of my middle bedroom. I have been using a Mac since about 2008 and I still consider myself a Mac Newbie.

Add ram to macbook pro retina late 2012