Authentication token not refreshing correctly

When an authentication token (such as a JWT) fails to refresh correctly, users may get unexpected logouts, 401 Unauthorized errors, or session expiration issues. This is a common issue in applications using token-based authentication with refresh tokens.

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1. Understanding the Token Refresh Process

How Token-Based Authentication Works

User Logs In: The server issues an access token (short-lived) and a refresh token (long-lived).
Access Token Usage: The client includes the access token in requests (e.g., via an Authorization: Bearer header).
Token Expiration: When the access token expires, the client sends the refresh token to get a new access token.
Token Refresh: If valid, the server issues a new access token without requiring the user to log in again.

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2. Common Issues When Refreshing Tokens

1. Expired or Invalid Refresh Token

If the refresh token itself is expired or invalid, the server will reject the refresh request, causing users to be logged out.

Fix:

Ensure refresh tokens have a reasonable expiry time (e.g., 7-30 days).
Implement automatic token rotation (generate a new refresh token after each refresh).
Store refresh tokens securely in HTTP-only cookies instead of localStorage.

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2. Refresh Token Not Sent in API Calls

If the client does not include the refresh token in the token refresh request, the server cannot issue a new access token.

Fix:

Check if the client includes the refresh token in the API request correctly.

Example (Correct Request Using Axios in JavaScript)

axios.post("/api/token/refresh", { refreshToken: localStorage.getItem("refreshToken") })
  .then(response => {
    localStorage.setItem("accessToken", response.data.accessToken);
  })
  .catch(error => {
    console.error("Token refresh failed:", error);
  });

If using cookies, ensure they are sent with the request:

axios.post("/api/token/refresh", {}, { withCredentials: true });

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3. Server Not Issuing a New Access Token

If the server fails to generate a new access token, the client remains stuck with an expired token.

Fix:

Verify that the server is correctly validating the refresh token and returning a new access token.

Example (Correct Express.js Implementation Using JWTs)

app.post("/api/token/refresh", async (req, res) => {
    const refreshToken = req.body.refreshToken;
    
    if (!refreshToken) return res.status(401).json({ error: "Refresh token missing" });

    jwt.verify(refreshToken, REFRESH_SECRET, (err, user) => {
        if (err) return res.status(403).json({ error: "Invalid refresh token" });

        const newAccessToken = jwt.sign({ userId: user.id }, ACCESS_SECRET, { expiresIn: "15m" });
        res.json({ accessToken: newAccessToken });
    });
});

Ensure jwt.sign() uses the correct user payload to generate a valid token.

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4. Not Handling Token Refresh on Expired Requests

If the access token is expired, but the client does not attempt to refresh it, users experience session expiration issues.

Fix:

Implement an interceptor in Axios to automatically refresh the token when a 401 error occurs.

axios.interceptors.response.use(
  response => response,
  async (error) => {
    if (error.response.status === 401) {
      const refreshToken = localStorage.getItem("refreshToken");

      if (refreshToken) {
        try {
          const response = await axios.post("/api/token/refresh", { refreshToken });
          localStorage.setItem("accessToken", response.data.accessToken);
          error.config.headers["Authorization"] = `Bearer ${response.data.accessToken}`;
          return axios(error.config);
        } catch (refreshError) {
          console.error("Token refresh failed:", refreshError);
        }
      }
    }
    return Promise.reject(error);
  }
);

This ensures that users do not have to manually refresh the page to get a new token.

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5. Refresh Token Being Revoked on Logout for Other Sessions

Some applications invalidate refresh tokens globally when logging out on one device, causing other active sessions to log out too.

Fix:

Implement refresh token revocation per device rather than globally.
Store multiple refresh tokens per user and invalidate only the one being used.

Example (Database-Based Refresh Token Storage in MongoDB)

const refreshTokens = {};  // Store refresh tokens per session

app.post("/api/logout", (req, res) => {
    const refreshToken = req.body.refreshToken;
    delete refreshTokens[refreshToken]; // Revoke only the used token
    res.status(200).json({ message: "Logged out successfully" });
});

This prevents logging out all sessions when logging out from one device.

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6. Incorrect Token Expiry Handling

Some applications miscalculate token expiration, leading to early session expiry.

Fix:

Ensure the client correctly checks token expiry before sending requests.

function isTokenExpired(token) {
  const decoded = JSON.parse(atob(token.split(".")[1]));
  return decoded.exp * 1000 < Date.now();
}

Refresh the token before it expires to avoid user disruptions.