iMac telling me drive cannot be used to start

[Dattdtee]

So before when I was on my iMac I tried to install Mojave. Said my Macintosh HD (only drive I have 1.12tb fusion) cannot be used to start up my computer. Which is obviously not true, because it does, everyday.
So I go to system restore. Erase the partition which is the full drive. Mac OS journal blah blah blah. Nothing left. Go to system restore to install it. Same problem. However now I have 0 os and it won’t let me install one. So any help would be appreciated. Thanks! Kevin!

 

[Cory Cooper]

Hello and welcome.

-Which exact model iMac?
-Were you running High Sierra previously?
-Does Disk Utility give the option to format it as APFS or only GUID Partition Map? I believe Mojave is the only version of macOS that will allow APFS on a Fusion Drive.

C