debugger-mode-hook is a variable defined in `debug.el'.
Its value is

  • This variable may be risky if used as a file-local variable.

Hook run after entering Debugger mode.
No problems result if this variable is not bound.
`add-hook' automatically binds it. (This is true for all hook variables.)

You can customize this variable.

This variable was introduced, or its default value was changed, in version 20.3 of Emacs.