How to Fix Flashing folder icon During macOS Boot or Installation

Apps Boot guide iMac macOSSonoma OpenCoreLegacyPatcher Performance
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How to Fix Flashing folder icon During macOS Boot or Installation

Boot failures need a predictable pass through firmware, USB, storage, EFI and verbose logs before reinstalling macOS. Most installer stalls come from firmware settings, an invalid config.plist, wrong SSDTs, bad USB mapping or unsupported storage/controller settings.

Quick Checks

  • Backup current state: Save a copy of your working EFI and run a full system backup before changing settings.
  • Identify hardware components: Note down your exact CPU, GPU, Wi-Fi card, and motherboard/laptop model.
  • Ensure utility alignment: Keep OpenCore, OCLP, and ProperTree updated.

Fix Steps

  1. Create a rollback point: Make a Time Machine backup and keep a copy of your last working EFI folder before editing OpenCore, kexts or root patches.
  2. Boot verbose: Add -v keepsyms=1 debug=0x100 so the final visible line gives a real clue.
  3. Check firmware settings: Disable Secure Boot and Fast Boot, set SATA to AHCI, disable CFG Lock if possible, and use UEFI mode.
  4. Validate OpenCore: Update OpenCore, Lilu and core kexts, then run ocvalidate or ProperTree clean snapshot.
  5. Recreate the installer: Use a fresh USB installer and try another USB port; older Macs may need a USB 2.0 hub for input during setup.
  6. Reset NVRAM: Reset NVRAM from the OpenCore picker before retrying the installer.

Do Not Continue If

  • Do not continue if: you do not have a working EFI backup, a Time Machine backup, or another bootable macOS installer.
  • Stop and capture evidence: if the machine stops booting, take a photo of the last verbose line before changing more settings.

Verify It Worked

  • Verbose boot moves past the previous stopping line.
  • The installer reaches Disk Utility and sees the target disk.
  • Keyboard, mouse and USB remain active during recovery.
  • OpenCore picker still loads after a cold boot.

Rollback

  • Restore the last booting EFI folder.
  • Use the officially supported macOS installer to recover the machine.
  • Do not erase the internal disk until the installer can boot twice consistently.

Next Action

  • Test now: reboot twice, reproduce the original problem, and confirm whether the same symptom returns.
  • If it still fails: record the Mac model, macOS build, OpenCore or OCLP version, GPU, Wi-Fi/Bluetooth chipset, and the last visible error.
  • Read next: use the related searches below for the nearest OpenCore or OCLP fix before making another change.

Related iATKOS Searches

Original Question: "Flashing folder icon?"

I have a Late 2013 iMac given to me by a family friend. I get to the boot selection screen fine and select efi boot. It starts and loads for a bit and gets to a screen where the apple logo is there and a bar at the bottom that says “about 29 minutes remaining”. It counts down for about 10 minutes or so then goes black and has a flashing folder icon in the middle of the screen and “support.apple.com/mac/startup” at the bottom.

Trying to upgrade to Sonoma.

Any ideas?

submitted by /u/JoeShtoops
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