Thanks Greg! Very clear! _______________________ Sent from MzK's phone. On Sun, Aug 2, 2020, 14:07 Gregory P. Ennis <PoMec at pomec.net> wrote: > Hello all-- > These instructions are somewhat OK but my messed up box is the only one > I've got basically to help with this problem. > > Where can we find "correction" instructions using a "rescue" CD or flash > drive? I understand RedHat provided detailed instructions to supported > customers. > > Thanks. > > _______________________ > Sent from MzK's phone. > > ---------- Forwarded message --------- > From: Alan McRae via CentOS <centos at centos.org> > Date: Sat, Aug 1, 2020, 19:22 > Subject: [CentOS] 8.2.2004 Quick recovery and fix for unbootable machines > To: CentOS mailing list <centos at centos.org> > > > This is a quick recovery and fix for the machines rendered unbootable > after the grub2/shim yum update. > > It is written for CentOS 8.2.2004 but similar should work for any CentOS > 8 or 7 as long as you get the correct shim file, > that is, the one from the latest installation media. > > I am running on an x86_64 architecture (see uname -i). Please use the > correct shim file for your architecture (shim-<arch>-15-11.el8.<arch>.rpm) > > I have tested this by breaking a machine and then recovering it. It > works for me. > > I hope someone finds it useful. Let me know. > > Regards > Alan > > HOW TO BOOT AN UNBOOTABLE MACHINE > ================================= > > 1) Download a copy of rEFind. This is a UEFI boot manager. Burn it to a > USB key. > > # wget -O refind.zip > > http://sourceforge.net/projects/refind/files/0.12.0/refind-flashdrive-0.12.0.zip/download > # unzip refind.zip > # cd refind-flashdrive-0.12.0 > # dd if=refind-flashdrive-0.12.0.img bs=4096 of=/dev/sdX (sdX is the > device for your USB key, this will be erased, use the whole device use > sdX not sdX1) > 1800+0 records in > 1800+0 records out > 7372800 bytes (7.4 MB, 7.0 MiB) copied, 0.980893 s, 7.5 MB/s > > 2) Turn off secureboot in your UEFI hardware. > > 3) Boot the USB key. You should get a colourful screen with icons and a > filename below. > > Use the left/right arrow keys to select the correct grubx64.efi. > Hit space to boot. > > Your usual grub menu should appear and the system should boot normally. > > HOW TO FIX THE PROBLEM > ===================== > > 1) We need to downgrade the shim package. Now your system is running get > an older copy of the correct shim package for your architecture > from the CentOS installation media (e.g. > CentOS-8.2.2004-x86_64-dvd1.iso) and install it. > > # mount CentOS-8.2.2004-x86_64-dvd1.iso /mnt > # cd /mnt/BaseOS/Packages > # cp shim-x64-15-11.el8.x86_64.rpm /root > # cd /root > # umount /mnt > > OR > > Get the package from a CentOS mirror: > > # cd /root > # wget > > http://ucmirror.canterbury.ac.nz/linux/CentOS/8.2.2004/BaseOS/x86_64/os/Packages/shim-x64-15-11.el8.x86_64.rpm > > 2) We can now reinstall the older shim package using yum. This will > downgrade the package to the working version. > > # yum install shim-x64-15-11.el8.x86_64.rpm > > Last metadata expiration check: 2:11:11 ago on Sun 02 Aug 2020 11:31:06 > NZST. > Dependencies resolved. > > > =========================================================================================== > > ========================================================================================= > Package Architecture Version > Repository Size > > =========================================================================================== > > ========================================================================================= > Downgrading: > shim-x64 x86_64 15-11.el8 > @commandline 647 k > > Transaction Summary > > =========================================================================================== > > ========================================================================================= > Downgrade 1 Package > > Total size: 647 k > Is this ok [y/N]: y > Downloading Packages: > Running transaction check > Transaction check succeeded. > Running transaction test > Transaction test succeeded. > Running transaction > Preparing : 1/1 > Downgrading : shim-x64-15-11.el8.x86_64 1/2 > Cleanup : shim-x64-15-13.el8.x86_64 2/2 > Verifying : shim-x64-15-11.el8.x86_64 1/2 > Verifying : shim-x64-15-13.el8.x86_64 2/2 > Installed products updated. > > Downgraded: > shim-x64-15-11.el8.x86_64 > > Complete! > > 3) Your system should now boot normally. > > 4) add "exclude=shim*" to /etc/yum.conf to prevent the broken one being > reinstalled. You should now be able to run 'yum update'. Remove the > exclude= when a proper fix becomes available. > > _______________________________________________ > > Dear List, > > I have had 6 of these problems and am on my way to the office to fix two > more. > > Here is what I did with an installation disc along with the advise from > the posts of Johny > Hughes. So far this has been easy to do and has worked every time. Make > sure your system > is connected to the network, and know your gateway address and a > reasonable ip address of > the machine for your network. > > #1. Boot to tine Install Disc and pick "Recovery Mode" > > #2. You will be given several options of recover Pick #1 to Continue > > #3. Use the 'chroot /mnt/sysimage' command to get into your system > > #4. Activate your network > > Find the device name you are going to use > > ip link > gives you the name as in 'enp3s0' as the device > > ip link set dev enpo3s0 up > activates the network card > > ip address add 10.0.0.67/24 dev enp3s0 > sets the card's address to 10.0.0.67 with a subnet mask of 255.255.255.0 > > ip route add default via 10.0.0.124 > sets the gateway for your machine to 10.0.0.124 > > #5. Make sure you have an active domain name service > > cd /etc/ > > vim resolv.conf > > Edit the appropriate value of > nameserver 10.0.0.124 > > (in my case the nameserver and gateway were the same machine) > > #6. Use of Yum > yum clean all > This necessary so that you can make sure you have the latest listings > > yum install shim > > For Centos 7 you want shim-x64-15-8.el7.x86_64 which Johnny Hughes just > released today. > > When this is installed you will also install mokutil-15-8.el7.x86_64 > > #7. Exit out of recovery mode, and reboot. > > This has worked for me every time. > > Thanks to everyone's advice on this list and all the good work done by the > Centos Team!!!! > > Greg Ennis > > > > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > https://lists.centos.org/mailman/listinfo/centos >