Please note that after upgrading to a new grub version, you should
first use "grub-install" to reinstall the bootloader.
Grub updated from 2.06 to 2.12 version.
After updating the system
sudo slapt-get -u
sudo slapt-get --upgrade
and install glibc glibc-i18n glibc-zoneinfo kernel-firmware if they ...

Try install slackware live to external disk and use it. So slackel after installation boots with huge-kernel 6.6.11. Slackware live use kernel 6.10.11
Wait for slakware live next edition with kernel 6.10.13 to check how it works. The problem appeared in kernel version.
I have no problem here running ...

If your system is working with huge kernel. Do not install generic kernel. Your system will be ok.
sudo slapt-get -u
sudo slapt-get --upgrade
sudo slapt-get -i wsdd2
sudo slapt-get -i glibc glibc-i18n glibc-zoneinfo

I think this is a hardware issue with acpi. Your pc is an Asus or dell ?
Or the ...

I found the bug in install-upgrade-kernel-ext-usb-gtk. Initrd has to created only for generic kernel. I am sure it is working.
After installed the system and boot.
We want to check if system boot with new kernel.
Type the commands without errors. Be careful.
1. sudo slapt-get -u

2. sudo slapt ...

After reinstall. To not do anything. I have to check the gui utility "Install-Upgrade generic kernel to external SSD disk or USB stick" do some tests.
Wait.

I found why system became unbootable. It was the grub package i upgraded it to 2.12 version. I revert it to old 2.06 version on repos.
Now boot with the system.

type sudo slapt-get -u
to not update the system to install everything. Just want to test if system boots. (and then update the system ...

No. wait.
I reinstalled in vmware. I do an update now. I will reboot and then i will update the kernel. To check.

I have done the installation many times to external usb stick or ssd disk and always worked.
I have to check it since huge kernel is removed from slackware and generic kernel is ...

How you do the installation?
Steps:
1. click on gparted. Create a gpt partition table. (click on Partition->New-> gpt)
2. create a vfat32 300MB partition for UEFI (/dev/sdc1.) After creation sign it esp,boot. (right click with the mouse on it and click on Manage flags. Click on boot) You will see ...

What internal disk or disks have on your computer. nvme or ssd?
Before installation be sure disk partitions slackel will be installed are clean or better create them again.
Then just do the installation using ext4 filesystem using the slackel64-mate 7.7 iso.
After installation do not upgrade the ...

vivaldi on slackel repositories is an old edition. I uploaded a recent version which is working.
type in mate-terminal
sudo spkg -d vivaldi-stable
sudo slapt-get -u
sudo slapt-get -i vivaldi
You will find vivaldi on menus under Applications -> Internet -> Vivaldi

I have upgraded the slackel-mate ...