Dear Андрей,

Am Samstag, 24. Oktober 2020 schrieb Андрей via Dng:
> Hello.
>
>
> On the last update of the kernel (5.9.0), nvidia-legacy-340xx driver
> would not compile because of some headers are missing. I have


I have had this experience a couple of times while upgrading. The
linux-headers for an updated kernel version don't seem to get installed
by dependency. The kernel is not really being updated, but the new
version is installed additionally. I've been surprised ever again by
this.

/etc/kernel/postinst.d/dkms:
Error! echo
Your kernel headers for kernel 4.19.0-12-amd64 cannot be found at
/lib/modules/4.19.0-12-amd64/build
or /lib/modules/4.19.0-12-amd64/source.

Installing the matching linux-headers solves it.

HTH

Kind regards,
Stefan

(@Андрей PS: sorry for the unintended private reply)