Error with Immutable Headers in Better Auth Session Middleware on Deno Server

Guys

Hello ,

I’m working on setting up session management using Better Auth with a Deno server and Hono as the framework. I followed the documentation to create a middleware for session handling, but I'm running into an issue when trying to retrieve sessions.

Here’s a simplified version of my code:

import { type Context, type Next } from "@hono/hono";
import { auth } from "../auth.ts"; // Import Better Auth instance

export const sessionMiddleware = async (c: Context, next: Next) => {
  try {
    var headers = c.req.raw.headers;
    // @ts-ignore
    const session = await auth.api.getSession({ headers });

    if (!session) {
      c.set("user", null);
      c.set("session", null);
      return next();
    }

    c.set("user", session.user);
    c.set("session", session.session);
    return next();
  } catch (error) {
    console.error("Error in sessionMiddleware:", error);
    // Return a 500 response if an error occurs
    return c.json({ error: "Failed to retrieve session" }, 500);
  }
};

export default sessionMiddleware;

import { type Context, type Next } from "@hono/hono";
import { auth } from "../auth.ts"; // Import Better Auth instance

export const sessionMiddleware = async (c: Context, next: Next) => {
  try {
    var headers = c.req.raw.headers;
    // @ts-ignore
    const session = await auth.api.getSession({ headers });

    if (!session) {
      c.set("user", null);
      c.set("session", null);
      return next();
    }

    c.set("user", session.user);
    c.set("session", session.session);
    return next();
  } catch (error) {
    console.error("Error in sessionMiddleware:", error);
    // Return a 500 response if an error occurs
    return c.json({ error: "Failed to retrieve session" }, 500);
  }
};

export default sessionMiddleware;

import { type Context, type Next } from "@hono/hono";
import { auth } from "../auth.ts"; // Import Better Auth instance

export const sessionMiddleware = async (c: Context, next: Next) => {
  try {
    var headers = c.req.raw.headers;
    // @ts-ignore
    const session = await auth.api.getSession({ headers });

    if (!session) {
      c.set("user", null);
      c.set("session", null);
      return next();
    }

    c.set("user", session.user);
    c.set("session", session.session);
    return next();
  } catch (error) {
    console.error("Error in sessionMiddleware:", error);
    // Return a 500 response if an error occurs
    return c.json({ error: "Failed to retrieve session" }, 500);
  }
};

export default sessionMiddleware;

import { type Context, type Next } from "@hono/hono";
import { auth } from "../auth.ts"; // Import Better Auth instance

export const sessionMiddleware = async (c: Context, next: Next) => {
  try {
    var headers = c.req.raw.headers;
    // @ts-ignore
    const session = await auth.api.getSession({ headers });

    if (!session) {
      c.set("user", null);
      c.set("session", null);
      return next();
    }

    c.set("user", session.user);
    c.set("session", session.session);
    return next();
  } catch (error) {
    console.error("Error in sessionMiddleware:", error);
    // Return a 500 response if an error occurs
    return c.json({ error: "Failed to retrieve session" }, 500);
  }
};

export default sessionMiddleware;

Issue Details

Upon running the server, I receive the following error:

Listening on http://localhost:8087/
Error in sessionMiddleware: TypeError: Cannot change headers: headers are immutable
    at Headers.set (ext:deno_fetch/20_headers.js:425:13)
    at Object.handler (file:///C:/Users/jacks/AppData/Local/deno/npm/registry.npmjs.org/better-auth/0.6.2/dist/plugins.js:1:38396)
    ...

Listening on http://localhost:8087/
Error in sessionMiddleware: TypeError: Cannot change headers: headers are immutable
    at Headers.set (ext:deno_fetch/20_headers.js:425:13)
    at Object.handler (file:///C:/Users/jacks/AppData/Local/deno/npm/registry.npmjs.org/better-auth/0.6.2/dist/plugins.js:1:38396)
    ...

Listening on http://localhost:8087/
Error in sessionMiddleware: TypeError: Cannot change headers: headers are immutable
    at Headers.set (ext:deno_fetch/20_headers.js:425:13)
    at Object.handler (file:///C:/Users/jacks/AppData/Local/deno/npm/registry.npmjs.org/better-auth/0.6.2/dist/plugins.js:1:38396)
    ...

Listening on http://localhost:8087/
Error in sessionMiddleware: TypeError: Cannot change headers: headers are immutable
    at Headers.set (ext:deno_fetch/20_headers.js:425:13)
    at Object.handler (file:///C:/Users/jacks/AppData/Local/deno/npm/registry.npmjs.org/better-auth/0.6.2/dist/plugins.js:1:38396)
    ...

The error occurs when the

getSession

getSession

getSession

getSession method is called, indicating that headers are treated as immutable. I attempted the workaround of using raw headers directly from

c.req.raw.headers

c.req.raw.headers

c.req.raw.headers

c.req.raw.headers, but this hasn’t resolved the issue.

Environment

Deno: 2.0.2
Better Auth: v0.6.2
Hono: v4.6.8

Jackson KasiOP•10/31/24, 12:51 PM

Steps Taken

Verified with auth.api.getSession({ headers })auth.api.getSession({ headers }) as shown in the documentation.
Attempted direct access to raw headers as a possible workaround.

Any insights into resolving this immutable headers issue would be greatly appreciated. Thanks for your help!

https://www.better-auth.com/docs/integrations/hono

Hono Integration | Better Auth

Hono Integration Guide

Jackson KasiOP•10/31/24, 12:52 PM

code: https://github.com/jacksonkasi1/better-auth-example/blob/dev/plugin-server/src/middleware/sessionMiddleware.ts

GitHub

better-auth-example/plugin-server/src/middleware/sessionMiddleware....

Contribute to jacksonkasi1/better-auth-example development by creating an account on GitHub.

Jackson KasiOP•10/31/24, 1:01 PM

Hey everyone,

I realized my issue with the immutable headers error was a simple oversight. I needed to clone the headers to avoid immutability. Here’s the quick fix:

// Clone headers to bypass immutability
const headers = new Headers(c.req.raw.headers);
const session = await auth.api.getSession({ headers });

// Clone headers to bypass immutability
const headers = new Headers(c.req.raw.headers);
const session = await auth.api.getSession({ headers });

This small change did the trick! Just sharing in case anyone else runs into the same thing.

Error with Immutable Headers in Better Auth Session Middleware on Deno Server

Guys

Issue Details

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