I am getting “code challenge required” when using IdentityServer4

I am pretty much sure that you are using version 4.0 or above. Let me know if I am correct?

In version 4.0 and above, the code flow + PKCE is used by default, as this is more secure than Hybrid flow according to the documentation.

Here is the link https://identityserver4.readthedocs.io/en/latest/topics/grant_types.html and link to relevant issue on github https://github.com/IdentityServer/IdentityServer4/issues/3728 describing it as a breaking change.

I also struggled with it for about 2 hours when I upgraded IdentityServer4 package to the latest version in one of my projects.

If you want to use Hybrid flow set RequirePkce to false in your client configuration.

"Clients": {
   /* Code removed for brevity */
      RequirePkce : "false"
    }