diskutil list 
	 
	/dev/disk0 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        +2.1 GB     disk0
   1:                  Apple_HFS macOS Base System       2.0 GB     disk0s1
/dev/disk1 (internal):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                         251.0 GB   disk1
   1:                        EFI EFI                     314.6 MB   disk1s1
   2:                 Apple_APFS Container disk2         250.0 GB   disk1s2
   3:       Apple_KernelCoreDump                         655.4 MB   disk1s3
/dev/disk2 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +250.0 GB   disk2
                                 Physical Store disk1s2
   1:                APFS Volume Macintosh HD - Données  195.9 GB   disk2s1
   2:                APFS Volume Preboot                 91.5 MB    disk2s2
   3:                APFS Volume Recovery                1.0 GB     disk2s3
   4:                APFS Volume VM                      2.1 GB     disk2s4
   5:                APFS Volume Macintosh HD            10.6 GB    disk2s5
/dev/disk3 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +5.2 MB     disk3
/dev/disk4 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk4
/dev/disk5 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk5
/dev/disk6 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk6
/dev/disk7 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +2.1 MB     disk7
/dev/disk8 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk8
/dev/disk9 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk9
/dev/disk10 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +12.6 MB    disk10
/dev/disk11 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +4.2 MB     disk11
/dev/disk12 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +1.0 MB     disk12
/dev/disk13 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +2.1 MB     disk13
/dev/disk14 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk14
/dev/disk15 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk15
/dev/disk16 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +1.0 MB     disk16
/dev/disk17 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk17
/dev/disk18 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +6.3 MB     disk18
/dev/disk19 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +6.3 MB     disk19
/dev/disk20 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk20
/dev/disk21 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +2.1 MB     disk21diskutil ap deleteVolume disk2s1 ; diskutil list disk2-bash-3.2# diskutil ap deleteVolume disk2s1
Started APFS operation
Deleting APFS Volume from its APFS Container
Unmounting disk2s1
Deleting Volume
Removing any Preboot and Recovery Directories
Finished APFS operation
-bash-3.2#
-bash-3.2# diskutil list disk2
/dev/disk2 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +250.0 GB   disk2
                                 Physical Store disk1s2
   1:                APFS Volume Preboot                 81.0 MB    disk2s2
   2:                APFS Volume Recovery                528.2 MB   disk2s3
   3:                APFS Volume VM                      2.1 GB     disk2s4
   4:                APFS Volume Macintosh HD            10.6 GB    disk2s5
-bash-3.2#diskutil list-bash-3.2# diskutil list
/dev/disk0 (internal):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                         251.0 GB   disk0
   1:                        EFI EFI                     314.6 MB   disk0s1
   2:                 Apple_APFS Container disk2         250.0 GB   disk0s2
   3:       Apple_KernelCoreDump                         655.4 MB   disk0s3
/dev/disk1 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        +2.1 GB     disk1
   1:                  Apple_HFS macOS Base System       2.0 GB     disk1s1
/dev/disk2 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +250.0 GB   disk2
                                 Physical Store disk0s2
   1:                APFS Volume Preboot                 80.9 MB    disk2s2
   2:                APFS Volume Recovery                528.2 MB   disk2s3
   3:                APFS Volume VM                      2.1 GB     disk2s4
   4:                APFS Volume Macintosh HD            10.6 GB    disk2s5
/dev/disk3 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +5.2 MB     disk3
/dev/disk4 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk4
/dev/disk5 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk5
/dev/disk6 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk6
/dev/disk7 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +2.1 MB     disk7
/dev/disk8 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk8
/dev/disk9 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk9
/dev/disk10 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +12.6 MB    disk10
/dev/disk11 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +4.2 MB     disk11
/dev/disk12 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +1.0 MB     disk12
/dev/disk13 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +2.1 MB     disk13
/dev/disk14 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk14
/dev/disk15 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk15
/dev/disk16 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +1.0 MB     disk16
/dev/disk17 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk17
/dev/disk18 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +6.3 MB     disk18
/dev/disk19 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +6.3 MB     disk19
/dev/disk20 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +524.3 KB   disk20
/dev/disk21 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               +2.1 MB     disk21
-bash-3.2#
-bash-3.2#diskutil eraseDisk jhfs+ "Macintosh HD" gpt disk0-bash-3.2# diskutil eraseDisk jhfs+ "Macintosh HD" gpt disk0
Started erase on disk0
Unmounting disk
Creating the partition map
Waiting for partitions to activate
Formatting disk0s2 as Mac OS Extended (Journaled) with name Macintosh HD
Initialized /dev/rdisk0s2 as a 233 GB case-insensitive HFS Plus volume with a 24576k journal
Mounting disk
Finished erase on disk0
-bash-3.2#C’est ça ! Quand je regardais mon disque, il était affiché en dessous « 10.15 » je ne comprends pas trop pourquoi... bref, installation lancé, je vous tiens au courant. Un grand merci en tout cas.Opération effectuée -->
- dans la fenêtre des 4 Utilitaires macOS > lance l'option : "Réinstaller macOS" > et choisis Macintosh HD comme destination lorsque cela te sera proposée. Cela te permettra une installation propre.
Note : il y avait manifestement une embrouille dans la distribution précédente du Conteneur. Je me demande même si l'OS qui démarrait n'était pas toujours Catalina...
 
	