End of Life Ruby 3.1 has reached end of life and gets no more fixes. Switch to Ruby 4.0 →

class method

ENV.freeze

static VALUE
env_freeze(VALUE self)
{
    rb_raise(rb_eTypeError, "cannot freeze ENV");
    UNREACHABLE_RETURN(self);
}

Raises an exception:

Example

ENV.freeze # Raises TypeError (cannot freeze ENV)

See also .filter! .has_key? .filter .has_value? also in 4.1 · 4.0 · 3.4 · 3.3 · 3.2 · 3.0