These are the few errors that I encountered while compiling a custom kernel(2.6.32 on Debian 6.0), and the workarounds that helped.
1.make-kpkg fails to generate initrd image.
You will have to copy initramfs from the examples in the kernel, i.e.
cp -a /usr/share/doc/kernel-package/examples/etc/kernel/postinst.d/initramfs /etc/kernel/postinst.d
2. mount: mounting /dev/disk/by-uuid/
To get around thing edit the grub entry and change the line
root=/dev/sdXY where X,Y are the paritions of your disk it could be /dev/sda1 or /dev/sdb1 etc... You can use gparted to find this out.
3. Ext3-Fs :sda1 couldn't mount because of unsupporte features.(204)
The cause of the error might be that your disk has ext4 filesystem and while compiling the kernel you have not enabled ext4 in the new kernel
Edit the .config file and set CONFIG_EXT4 to "y".
Now recomile the kernel and try booting again.