EFI sys partition error 69766 & sudo fsck_msdos

[PliSsK]

My dual boot system was working normally, with Catalina and Win 10 on the same 970 Evo+ NVMe drive (latest firmware) and both Clover and Win Boot Manager in the first EFI partition. When I performed Disk Utility First Aid on all the devices, the main EFI repair failed with the error 69766 stating that the EFI system partition file system needed repairing. I found the solution here and performed sudo fsck_msdos disk0s1 (checked that this was the correct disk number for the EFI partition):

<< Solved >> - The partition map needs to be repaired because there's a problem with EFI system partition's file system.

After upgrade to 14.15,I used the disk util to check disk for errors, get: The partition map needs to be repaired because there's a problem with EFI system partition's file system. I use usb to boot, and use diskutil to fix the partition. But the problem remains after reboot.

www.tonymacx86.com

EFI partition checked out ok in Disk Utility, but ever since then, I started having problems with Windows and Catalina crashing shortly after log in. At first the problem was just with windows, with occasional crashing after starting up and opening up a browser window (within 1-2 minutes of logging in). However it increased in frequency and is now every time, so Windows is completely unusable. The most common error message in Windows has been WHEA Uncorrectable Error (a hardware failure warning), and less frequently I have had IRQL NOT LESS EQUAL and Clock Watchdog Timeout. Also I am now having the same issues with Catalina crashing albeit less frequently, although it's been getting worse. Sometimes the computer just resets, other times Catalina just freezes. About 2/3rds of the time when OS X does boot up, it is ok and remains useable for many hours doing all kinds of tasks

I am having no issues booting up another drive, e.g. Linux USB or OS X Install USB, from Clover on the main NVMe EFI partition. Having same problems booting up Catalina & Win 10 from EFI partitions on different drives. Same issue with Win 10 if I boot it directly from the Win Boot Manager from BIOS on the same drive or from another drive.

DriveDx shows no drive errors and Samsung Magician shows it is healthy.

The EFI partition error code 69766 is back again now, so I am wondering if it is worth trying to reset the file system to msdos again (as it can't get any worse?) or perhaps recreate the EFI partition as FAT32 in Linux with the appropriate flags and copy the EFI files back to it. Last resort would be to reformat the entire drive and repartition it.

 

[PliSsK]

I performed sudo fsck in Linux on the Mac EFI partition and restored from back up to original and fixed some discrepancy, and now at least OS X seems to be boot up ok. However, Windows is still a basket case, I can boot it up but it crashes every time shortly afterwards. Perhaps reinstalling windows is the only remaining solution. I tried replacing the Microsoft folder in the EFI partition with an older one from a 2 month old back up when everything seemed to work ok and I got a checkerboard screen after log in, seems kaput.

Edit: Had to reinstall windows completely and now it all works ok.

 

[ed.stein]

I had the exact same problem updating from 10.14.4 to 10.15.5, but the solution for me was to boot into recovery, open disk utility to find out the name of my EFI partition and:

diskutil repairVolume disk0s1

Where disk0s1 is your EFI partition.