401 error ka matlab "Unauthorized" error hota hai. Yeh tab aata hai jab client (user) ko requested resource ko access karne ke liye authentication karni hoti hai, lekin ya to authentication fail hoti hai ya phir authentication headers missing hote hain.
Key Differences from 403 Error:
- 401 Error : Iska matlab hai ki client ko authenticate karne ki zarurat hai (jaise username/password ya token) aur bina authenticate kiye resource access nahi kiya ja sakta. Server kehta hai ki "Pehle authenticate karo, phir access mil sakta hai."
- 403 Error : Isme client authenticated ho sakta hai, lekin usse access ke liye permission nahi hoti. Server kehta hai ki "Tum authenticate ho, lekin access ki permission nahi."
Common Causes of 401 Error:
1. Missing Authentication : Request mein required credentials (jaise API key, token, ya username/password) nahi diye gaye hote.
2. Invalid Credentials : Agar client ne galat credentials provide kiye hain.
3. Token Expiry : Agar authentication token expire ho gaya ho, to 401 error aata hai.
4. Incorrect Authentication Method : Agar server ko specific authentication method (jaise Bearer Token, Basic Auth) chahiye aur client ne galat method use kiya ho.
Example:
Agar tumhari API request ke liye authentication token nahi diya gaya, to response kuch aisa ho sakta hai:
401 Unauthorized
You must authenticate before accessing this resource.
Yeh error resolve tab hota hai jab client valid credentials ya authentication details provide karta hai.
