I installed Ubuntu 24.04 server on a physical server. My kernel version is:

# uname -r
6.8.0-38-generic

Using the Ubuntu 24.04 I just installed, I followed the instructions at:

https://wiki.ubuntu.com/Kernel/BuildYourOwnKernel

I obtained the source using apt rather than git. Here is what was downloaded:

# ls -al
total 226600
drwxrwxr-x  4 root root      4096 Jul 17 16:32 .
drwxrwxrwx  6 root root        65 Jul 17 15:08 ..
drwxr-xr-x 29 root root      4096 Jul 17 16:32 linux-6.8.0
-rw-r--r--  1 root root   1919488 Jun 10 10:49 linux_6.8.0-38.38.diff.gz
-rw-r--r--  1 root root      9222 Jun 10 10:49 linux_6.8.0-38.38.dsc
-rw-r--r--  1 root root 230060117 Mar 15 09:29 linux_6.8.0.orig.tar.gz
drwxr-xr-x  3 root root        83 Jul 17 17:01 linux-signed-6.8.0
-rw-r--r--  1 root root      2620 Jun 10 10:49 linux-signed_6.8.0-38.38.dsc
-rw-r--r--  1 root root     26760 Jun 10 10:49 linux-signed_6.8.0-38.38.tar.xz

I do not have to modify any configuration files.

Then I set the current directory to the root of the kernel directory I downloaded:

# cd linux-6.8.0

The next step does not work:

# fakeroot debian/rules binary-headers binary-generic binary-perarch
fakeroot: FAKEROOTKEY set to 724713999
fakeroot: nested operation not yet supported

I have not been able to figure out what I am doing wrong?