We have few iMacs of 2017 model running on Mac os Mojave (10.14.2). After upgrading OS from High Sierra (10.13.6) to macOS Mojave (10.14.2) machines started restarting with flashing folder with question mark icon and the issue resolves temporarily with a PRAM reset, again after sometime the machine restarts with a flashing folder and we are unable to get the root cause why this issue occurs. We tried multiple things by re-installing the macOS , upgrading OS to 10.14.4 , using combo update to 10.14.4 , putting imacs in logout mode e.t.c., but none of them works. We ran hardware tests and found out that issue is not with the hardware.
Question
Flashing folder with Question mark after Mojave update
+3
+12The Flashing folder with a question mark, means there is no useable OS in the location it is looking for one.
Try looking at your Startup disk settings.
If you hold down "alt" at boot it will show you a list of all bootable drives available, check for the local HD and choose that. Then when it boots open up System Preferences, and then startup disk, and make sure it is set to the local HD. If it is set try setting it to a different one and then setting it back to the HD again.
I am guessing it gets set to the mounted dmg from the OS install app, and is supposed to switch back to the local HD but some gremlin has decided to not change it. Or the blessing of the local HD has failed, you can sort that in Terminal, cant remember the command, but Google it and you will find the right one.
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