Hi @late-needle-23869, this is almost certainly due to misconfiguration or a wrong parameter somewhere. Hydra does support PKCE. Did you set the client auth method to none? (if you created the client using the hydra cli, the argument is something along the lines of

--token-endpoint-auth-method none

Thank you very much, 🙂 the flag it works without problems the truth is that I checked it in the documentation but I thought that by enabling it I was disabling the security.