On Sun, 29 Jan 2023 15:44:44 +0200 Eli Zaretskii <eliz@gnu.org> wrote:

> To reproduce:
>
>   emacs -Q
>   M-x keymap-local-set
>   C-c .
>   forward-line RET
>
> Observe the error message:
>
>   [3 46] is not a valid key definition; see ‘key-valid-p’
>
> (The error message comes from keymap--check.)
>
> To type the key sequence, I actually pressed Ctrl and typed 'c', then
> released Ctrl and typed '.'.  Isn't that what one is supposed to use?
>
> So the above basically makes keymap-local-set useless, or am I missing
> something?  The following does work:
>
>   M-: (keymap-local-set "C-c ." 'forward-line) RET
>
> However, I could find no way of typing the string "C-c ." at the
> prompt of keymap-local-set.

This patch seems to DTRT: