MP 1,1-5,1 Update seems to have ruin my boot drive.

[Rezar]

Hadn't turned on my Mac Pro 4,1 in a while and it wanted to update so I let it.

Not sure what happened but now when it starts up it displays the prohibition sign - if I let it be it will load into my windows bootcamp.

I see that the prohibit sign is supposed to mean that there is a mismatch between the OS-version and my hardware (I have a 4,1 flashed to 5,1 and RX580 - I obviously had to install another card to get the boot screen) but I don't see how that could be the case, I mean the update probably wouldn't update to an unsupported version!

So it seems like the macOS drive has been rendered unusable (the drive I use is a Samsung PCIe drive).

My actual problem is I don't have another Mac so I don't know how to reinstall macOS?

 

[MarkC426]

What version of MacOS do you have installed.
Do you know your bootrom version.

 

[DeltaMac]

There's more possibilities than just "mismatch between OS-version and hardware".
The prohibited symbol can mean that your installed version has a corrupted/damaged file in the boot system.

But, yes, can you tell us what update version you installed?

 

[Rezar]

I'm sorry - I didn't do the obvious - reset the NVRAM - it boots now, sorry for wasting anyone's time.

Still something going on since it ejects the CD-tray like with a firmware upgrade when starting up!

OS: 10.14.6
Firmware: 144.0.0.0

 

[DeltaMac]

NVRAM reset also removed the default boot drive setting.
Open your System Preferences, then Startup Disk pane. Unlock that pane, then select your boot drive in that window.

 

[Rezar]

^ thanks, it fixed it.