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[kmbaroyale19]

The 256GB SSD was in fact not signed into iCloud but it is now. I only have one ID. When I signed in, various apps and categories were visible as would be expected. Then I closed the App Store window and when I reopened it, it was blank. When I click on AppStore in the menu at the top I see that it is open because of the option "Quit App Store". Unfortunately, when I try to make a screenshot the small menu closes so I have added a photo of the screen. I have also checked that my iPhone and iPad 6 and iPad 2 are signed in. Now I will switch back to the 512 GB internal SSD

 

[kmbaroyale19]

I am now back on the 512 GB internal SSD and have signed in all of my devices which are now visible. I made a screenshot but when I click on "Attach files" the wheel spins and after 5 minutes I have to Force Quit Chrome. I am still unable to open App Store, Thunderbird, Firefox, Notes, Calendar, Microsoft Word / Excel and all of the other programmes. All of these work normally on the old 256 GB SSD.

 

[Rod]

Okay, honestly I know what Apple help lime would say and I’m so stumped I’m incline to go down the same track and that is to reinstall the macOS. If there is no unique data on the 512GB drive I would be inclined to erase it and reformat it first.

 

[Rod]

To do this you will need to download the installer for Big Sur. I would suggest you do this on the 256GB drive. You will then need to create a USB macOS installer. This is done with free software, I use Instal Disk Creator from MacDaddy - Easy to use but powerful software. Made to high standards.
You will need a USB thumb drive about 25GB in size. You select the Big Sur installer in the Instal Disk Creator window and the USB drive as target and start. It will erase the USB drive and create a Bootable USB Installer.
Boot your device from the USB drive by Pressing the Option key at startup and use Disk Utility in the menu to erase the Macintosh HD. You will need to unmount the volumes in the Macintosh HD first. Just right click on them in Disk Utility and select Unmount or use the Tool Bar command on the window. You will need to name the drive (Macintosh HD) choose APFS as Format and GUID as Mapping option if asked.
Now you can quit DU, return to the installer and open Instal macOS. From there its an automated process until setup.
Here you need to login with your Apple ID and complete the other usual steps like Time Zone, Language, Email accounts etc.
In the end you will have a brand new OS just like a new device. You can then connect your 256GB drive via its enclosure and drag what you want to the new drive.
Of course it would be a good idea to ensure the 512GD drive is working as it should befor going to the trouble of installing all your data. At the end of the day your problems could all be attributable to a faulty or dieing SSD.

 

[kmbaroyale19]

Rod,
I have found the USB stick that I referred to last week. When I view it on Disk Utility I see that the title is "Install macOS Mojave". However it has only 8GB.
Should I:
a. Use this installer as it is?
b. Download a new installer on this stick?
c. Obtain a new 25GB stick and download a new installer as you have described?
I have 64GB SanDisk SD card. Can I use this or must it be USB?

 

[Rod]

How was the "Install macOS Mojave" USB stick created? Will it boot your device?
If so then yes you could erase the HD (following the same instructions as I gave you in post #24) with that, instal Mojave, set up as normal then Upgrade to Big Sur. The time and effort is about the same if not a little less.
Read this paragraph "How to update a Mac running macOS Mojave or later to Big Sur" at this site: https://www.businessinsider.com.au/how-to-update-mac-2019-5?r=US&IR=T
Basically you just go the the Apple Menu > System Prefs > Software Update and wait till it finds the Big Sur update.

 

[Rod]

Bear in mind I cant guarantee that this will fix the problems but it will eliminate a lot of possible causes.

 

[kmbaroyale19]

How was the "Install macOS Mojave" USB stick created? Will it boot your device? - Good questions.
I most certainly followed the instructions on some website or forum.
I have just booted from the USB stick and now have the screen shown in the attached photo.
I am writing this on my old 1997 MacBook so can "multitask" with you.
Please advise what I should do. Don't worry, I won*t hold you responsible for the result

 

[Rod]

Open Disk Utility and select the Show All devices option in the view Tab.
Select the Media which should be at the top of the list, It should be an SSD of some sort.
You now need to erase it. Its Possible this was not done before.

 

[kmbaroyale19]

This is what I have

 

[kmbaroyale19]

This is what MacBook Pro - Data (which is greyed out) shows

 

[kmbaroyale19]

Sorry, I didn't read your instruction fully.
I have now chosen Show All Devices and erased the SSD at the top.
This is what I now have.

 

[kmbaroyale19]

UPDATE
When I tried installing the Mojave OS I got a message saying that it was damaged. Having no more to lose I connected my TimeMachine HD - the same one that, last week, showed the latest backup to be sometime in 2019. Today it shows the most recent to be 26.06.2021, so I went for it.
Currently there are 14 minutes remaining.

 

[kmbaroyale19]

Too good to be true. I have tried the last 4 backups but the Installer Log shows that they all contain thousands of errors and only about 12 GB is installed. I even got an Error message when I tried to delete the internal SSD in Disk Utility.
I still have the old SSD which hopefully hasn't become corrupted and still works.
I will take some out-time from this. Thankfully the old MacBook is still working.
Many thanks.

 

[Rod]

You have an additional problem with that SSD, it‘s encrypted. This is something I and dare I say most of the members here strongly discourage. It’s fine, although totally unnecessary, until there is a problem with the Operating System then it prevents normal access and in the worst cases renders the HD useless. Decrypting a damaged SSD is often impossible and without doing so repairs cannot be made.
However it appears that you have successfully erased the SSD in your post #32 so now your problem is probably that the old Mojave installer‘s certificate has expired which is why it comes up with an error. You can restore the certificate but that’s another process.
You may need to erase the SSD again due to the failed restore with Time Machine which reflects the errors that you had on the SSD.
So, we are back at the original suggestion of creating a Big Sur bootable USB installer.
If you wish to go ahead with that I have already given you the instructions and you are welcome to ask any further questions.
When you do get this fixed I suggest you erase your TM backup too and start afresh. No point in having a backup of a corrupted HD.

 

[kmbaroyale19]

Thank you once again Bob.
I will buy a 25GB stick and have a go at creating a Big Sur installer
I wanted a download from the AppStore but, once again, can't access it - see screenshot - why is the screenshot grey?
Yesterday I was able to access the AppStore without a problem and my devices were visible on all other devices.
I have just now logged into iCloud.com and now all devices are visible but I still can't access the AppStore.

 

[kmbaroyale19]

I have created a Big Sur Installer but on a small 80GB external USB HD. Will this work or must it be a stick? I found the HD while looking for something else.
Before ruining the weekend for myself and my wife (happy wife, happy life), my 256GB SSD which will be the source is formatted APFS (Case-sensitive, Encrypted). Logic implies that both the 80GB Installer and the internal SSD must also be so formatted. Is this correct?
Have good weekend.

 

[Rod]

I think I have mentioned what a PITA encryption is in a past post and because I have never used it I have to admit I do not know the answer to that question.

 

[kmbaroyale19]

Well, here we are. I appear to have a brand new Mac with nothing on it. I have downloaded and installed Thunderbird which works but, of course, only has 78 mails. I also installed NordVPN which I always have running.
The HD is not showing on the desktop. The screenshots show that it is not mounted but clicking on the Mount button has no effect. Google says that there is a box "show these items on the desktop" under preferences "General" but I don't have that.
If all works out well, how do I transfer my stuff from the old 256GB SSD? Or is it not going to work?
Does this at least mean that the 512GB SSD has not been killed?
Many thanks for getting me so far.

 

[MacInWin]

Everything seems to be ok. Open Finder, click on the word Finder in the top bar, then preferences and select what you want to see under the General and Sidebar tabs. Note: In your images you can see the various Volumes in Container 1 on the SSD. Finder will logically merge Macintosh HD and Macintosh HD - Data into one icon on the desktop named Macintosh HD.

To transfer the information from the other drive, you can use either Finder to copy the files from one to another, although that may lead to some ownership issues down the road. You have, apparently, already created a new account on the newly installed system and the files on the other drive are owned by the old account (yes, the system knows the difference) so you may find them to be read only at first. What you might want to consider, now that you know the SSD is good and how to install the OS is to do it again, and this time when it first boots and you start setting it up when it offers to migrate your data, take the offer and migrate the data from the small drive. That way the migration process will sort out the ownership for you and you will end up with an account just like you had before, with the name and login just as it was and everything were it was before you started.