(UndefinedFunctionError) function :crypto.hmac/3 is undefined or private

I’m failing to render any page, the application takes giving me the following error

[error] #PID<0.1204.0> running ElixirWeb.Endpoint (connection #PID<0.1203.0>, stream id 1) terminated
Server: localhost:8080 (http)
Request: GET /
** (exit) an exception was raised:
    ** (UndefinedFunctionError) function :crypto.hmac/3 is undefined or private
        (crypto 5.0) :crypto.hmac/3
        (plug_crypto 1.2.0) lib/plug/crypto/key_generator.ex:81: Plug.Crypto.KeyGenerator.generate/7
        (plug_crypto 1.2.0) lib/plug/crypto/key_generator.ex:67: Plug.Crypto.KeyGenerator.with_cache/3
        (plug_crypto 1.2.0) lib/plug/crypto/key_generator.ex:51: Plug.Crypto.KeyGenerator.generate/6
        (plug 1.11.0) lib/plug/session/cookie.ex:114: Plug.Session.COOKIE.put/4
        (plug 1.11.0) lib/plug/session.ex:94: anonymous fn/3 in Plug.Session.before_send/2
        (elixir 1.12.0) lib/enum.ex:2356: Enum."-reduce/3-lists^foldl/2-0-"/3
        (plug 1.11.0) lib/plug/conn.ex:1691: Plug.Conn.run_before_send/2
        (plug 1.11.0) lib/plug/conn.ex:407: Plug.Conn.send_resp/1
        (phoenix 1.5.6) lib/phoenix/endpoint/render_errors.ex:78: Phoenix.Endpoint.RenderErrors.instrument_render_and_send/5
        (phoenix 1.5.6) lib/phoenix/endpoint/render_errors.ex:64: Phoenix.Endpoint.RenderErrors.__catch__/5
        (phoenix 1.5.6) lib/phoenix/endpoint/cowboy2_handler.ex:65: Phoenix.Endpoint.Cowboy2Handler.init/4
        (cowboy 2.8.0) ~/elixir/deps/cowboy/src/cowboy_handler.erl:37: :cowboy_handler.execute/2
        (cowboy 2.8.0) ~/elixir/deps/cowboy/src/cowboy_stream_h.erl:300: :cowboy_stream_h.execute/3
        (cowboy 2.8.0) ~/elixir/deps/cowboy/src/cowboy_stream_h.erl:291: :cowboy_stream_h.request_process/3
        (stdlib 3.15) proc_lib.erl:226: :proc_lib.init_p_do_apply/3
1 Like

Try to update plug_crypto library. It uses :crypto.hmac/3 which was removed in OTP 24.
As you can see on GitHub, newer version of plug_crypto supports OTP 24 plug_crypto/key_generator.ex at 6ba8fd42a68351459fe6c769ca04aea6022a5cd1 · elixir-plug/plug_crypto · GitHub


By this error I have just know now mix there are more interesting options :smiley:
Example: mix deps.update --all


In case you are using a pure Elixir implementation without Plug.

:crypto.hmac/{3,4} is deprecated and is removed in Erlang/OTP 24.

:crypto.mac/4 should be instead, but it is available only since Erlang/OTP 22.1.

Both functions yield the same result:

iex(6)> :crypto.mac(:hmac, :sha256, "key", "data") == :crypto.hmac(:sha256, "key", "data")
iex(7)> :crypto.mac(:hmac, :sha384, "key", "data") == :crypto.hmac(:sha384, "key", "data")

updated this dependency but still facing the same issue.
Pls help

Could you show the stacktrace?