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Strange MacBook Pro 2015 boot issue  



has anyone ever run into an issue where your MacBook Pro has a very slow boot progress bar, and ends up with a message “macos could not be installed on your computer” upon power up. This has happened twice now for no apparent reason. After a short delay it dumps and installation log, and goes into a mode where I can access some utilities like disk utility, etc. One of the options is to choose a startup disk, and after pointing to my internal drive, the next boot up works like a champ. I’m trying to narrow down how I get into this mode in the first place, as I am NOT booting into recovery mode (by hitting option R) after hitting power button. I’ve already been to Genius Bar last month(no help from them) and now a call to technical adviser at apple. They had me reinstall the OS.

Anyone ever see this behavior? It’s like the startup disk info in the SMC and or PRAM is getting trashed for some reason. So the machine randomly doesn’t know what the startup disk is.. the question is if this is true, what could be clobbering the SMC.


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1 Answer

I agree that it sounds like a PRAM flag getting incorrectly set, or possibly some bad plist entry that indicates an incomplete installation. 

But I wonder if this is acting in combination with an intermittent error of some sort with your HD. ie. startup manager fails to read the default volume for startup, then reverts to the recovery partition, and the recovery partition still has a flag in it's own plist that says installation didn't complete.

You don't mention what version of the operating system you are currently on. That screenshot appears to be from the High Sierra (10.13) installer. 

My inclination would be to try to do a reinstall from a USB thumb drive of whatever operating system you need .

Yes It is high Sierra. I’ve done a full reinstall, per apple support recommendation , via recovery mode.  The key for me is to narrow this down before my apple care runs out in February. 

I have a working theory that I am going to test tomorrow. I have an external 1TB Samsung evo 860 bootable clone (I use carbon copy). 

Whenever I clone my drive, even an incremental clone, I’m now in the habit of testing that I can boot from the clone. Now this weirdness has happened only twice mind you in the past two months, but in both cases I think it was after I booted off this external SSD. I NEVER  saw this when my external clone was a rotational disk. So tomorrow I’m going to try and boot off the SSD and see if I can duplicate the problem. 

I’ve got a scheduled call back from apple technsupport tomorrow, I’d like to know if I’ve got a subtle hardware issue, that I get it fixed before my AppleCare runs out.