My box is mid 2012 MacBook Pro, 1 TB HD, Sierra 10.12.6. It has dual-booted with Ubuntu using rEFInd until the High Sierra installation failed, after which I only used Ubuntu. After uninstalling rEFInd I'm attempting to upgrade the macOS side to Mojave and get the error above. I've already run First Aid on the Macintosh HD. Here's the partitioning:
# diskutil list disk0
/dev/disk0 (internal, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *1.0 TB disk0
1: EFI EFI 209.7 MB disk0s1
2: Apple_CoreStorage Macintosh HD 500.4 GB disk0s2
3: Apple_HFS Recovery HD 650.0 MB disk0s3
4: Linux Filesystem 498.8 GB disk0s4
# gpt -r show disk0
gpt show: disk0: Suspicious MBR at sector 0
start size index contents
0 1 MBR
1 1 Pri GPT header
2 32 Pri GPT table
34 6
40 409600 1 GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
409640 977270656 2 GPT part - 53746F72-6167-11AA-AA11-00306543ECAC
977680296 1269536 3 GPT part - 48465300-0000-11AA-AA11-00306543ECAC
978949832 974313152 4 GPT part - 0FC63DAF-8483-4772-8E79-3D69D8477DE4
1953262984 262151
1953525135 32 Sec GPT table
1953525167 1 Sec GPT header
Is there a way to install Mojave without reformatting?