I can’t reinstall the macOS Sierra on my MacBookPro

Which OS was on the mac before you tried to install macOS Sierra.

If the mac had been running High Sierra, Mojave, Catalina, Big Sur or Monterey then the Disk would have been formatted

as APFS. macOS Sierra can only run on Disks formatted as Mac OS Extended (Journaled).

Were you trying to do an Erase and Reinstall from your Recovery HD and the Apple Recovery Servers.

Not a good idea.

Let's try this.

Restart your mac to your Recovery HD, select Disk Utility and press Continue.

Click View in the menubar and select Show All Devices.

Highlight the Disk in the left hand panel, the Disk will be called Apple SSD.... or something similar.

(Do not highlight any of the indented Volumes)

Click Erase,

Give the Disk a name.

Format: Mac OS Extended.

Scheme: GUID Partition Map.

Click Erase.

When Done quit Disk Utility.

If you want to try and reinstall macOS Sierra from Apples Recovery Servers read below.

The certificates for several of Apples OS's expired in October 2019, Apple haven’t bothered getting these updated on 

their Recovery Servers with valid certificates. 

This often results in the error 'no packages were available for download'. 

Try this workaround, we are going to set the time and date on your mac to a date previous to the expiry date of the certificates.

Connect your mac to your router via cable, not WiFi

Boot to your Recovery HD, click on Utilities in the menubar select Terminal.

Make sure WiFi is switched off, it can reset the date back to today.

Enter a new date, for example or just copy and paste

sudo date -u 011421002017

press Return

enter your password

press Return

If Terminal returns an error saying sudo : command not found, then try again without sudo.

just enter 

date -u 011421002017

press Return

You won't be prompted for a Password if you did not need to use sudo

Once the date has changed you can quit Terminal.

Now try downloading the OS.

Click on Install OS X, press Continue.

If this works then when the OS is installed and booted up you can Open System Preferences> Date & Time

and reset the time back to today.

If the above does not work then you will need to borrow a mac that is capable of running macOS Sierra and

create a bootable USB installer on hat mac.

Open Safari and click on this link,

How to get old versions of macOS - Apple Support

Go to Use Safari to download macOS to your mac.

Click on macOS Sierra.

This will download InstallOS.dmg to the Downloads folder.

Double-click InstallOS.dmg to get the InstallOS.pkg

Double-click on InstallOS.pkg and an installation window will open.

This does not install Sierra but will create Install macOS Sierra.app in your Applications folder.

If you are asked to select a destination disk for this make sure you select your macs internal drive.

There is a problem with making a bootable USB installer with the Install macOS Sierra.app

where it returns an error Volumes/<USBname> is not a valid mount point. There is a workaround.

With Install macOS Sierra.app in your Applications folder open Terminal.

Paste in this command

sudo plutil -replace CFBundleShortVersionString -string "12.6.03" /Applications/Install\ macOS\ Sierra.app/Contents/Info.plist

press return

enter your password

press return

now paste in the createinstallmedia command for Sierra where MyVolume can be replaced with the name of your USB stick

If your USB name has more than one word separated by spaces you would need to type it in as

/The\ USB\ Name

sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install\ macOS\ Sierra.app

press return 

follow the prompts

The process takes around 30 minutes to complete, be patient, Terminal will look like it is not

doing anything but it is.

When it has completed you can eject the USB, and insert it directly to your mac.

Restart the mac while pressing the option/ alt key.

In a minute or two you will see the Startup Manager select the USB and press Return.

After the mac has booted to the USB you will see a Utilities screen.

If you had reformatted the mac to Mac OS Extended (Journaled) as described earlier you can just

click on Install OS and press Continue. The installation process should begin, follow the prompts.

If you had not reformatted the Disk earlier then you would select Disk Utility and reformat as described

earlier, please note that on older OS's (macOS Sierra and older) there is no View option on the menubar

and therefore no Show All Devices option for these older versions of Disk Utility.

Highlight the Disk and press Erase then name and format as before.

Quit Disk Utility.

Select Install OS, press Continue.

Keep the USB in a safe place, do not rely on Apples Recovery Servers.

Were you trying to erase in in Restore Mode?

Repair a storage device in Disk Utility on Mac

Disk Utility can fix certain disk problems—for example, multiple apps quit unexpectedly, a file is corrupted, an external device doesn’t work properly, or your computer won’t start up. Disk Utility can’t detect or repair all problems that a disk may have.

If you run First Aid on a disk, Disk Utility checks the partition maps on the disk and performs some additional checks, and then checks each volume. If you run First Aid on a volume, Disk Utility verifies all the contents of that volume only.

1. In the Disk Utility app  on your Mac, choose View > Show All Devices.
2. Note: If you’re checking your startup disk or startup volume, restart your computer in macOS Recovery, select Disk Utility in the macOS Utilities window, then click Continue. If you check your startup volume (Macintosh HD), make sure you also check your data volume (Macintosh HD - Data).
3. 
   
4. In the sidebar, select a disk or volume, then click the First Aid button .
5. If Disk Utility tells you the disk is about to fail, back up your data and replace the disk—you can’t repair it. Otherwise, continue to the next step.
6. Click Run, then click Continue.
7. If Disk Utility reports that the disk appears to be OK or has been repaired, you’re done. You can click Show Details to see more information about the repairs. Otherwise, you may need to do one of the following.

• • If Disk Utility reports “overlapped extent allocation” errors, two or more files occupy the same space on your disk, and at least one of them is likely to be corrupted. You need to check each file in the list of affected files. Most of the files in the list have aliases in a DamagedFiles folder at the top level of your disk.
    • If you can replace a file or re-create it, delete it.
    • If it contains information you need, open it and examine its data to make sure it hasn’t been corrupted.
  • If Disk Utility can’t repair your disk, or you receive a report that the First Aid process failed, try to repair the disk or partition again. If that doesn’t work, back up as much of your data as possible, reformat the disk, reinstall macOS, then restore your backed-up data.

If your Mac has a Fusion Drive and you see a flashing question mark or alert, see the troubleshooting section of the Apple Support article About Fusion Drive, a storage option for some Mac computers.

If you continue to have problems with your disk or it can’t be repaired, it may be physically damaged and need to be replaced. For information about servicing your Mac, see Find out how to service or repair your Mac.

Any clues here?

Sierra won’t install to SSD, thanks to Eau Rouge…

https://discussions.apple.com/thread/251358124?answerId=252770772022#252770772022