Question

My script worked locally but fails on the server during the login flow Is a CSRF token missing

Answer 1

Yes, a missing or invalid CSRF token is one of the most common reasons a login flow works locally but fails on a server. 

This usually happens when

1. Moving from browser to headless server

2. Switching environment 

3. Deploying to dockers/kubernetes

4. Using requests instead of browsers

5. Automating SSO/OAuth flows

The most common symptoms you might observe is 

1. Login page reloads silently 

2. HTTP 403 

3. Redirect loop

4. “Invalid session”

5. “Forbidden”

6. Authentication succeeds locally only 

Know what is CSRF - Cross Site Request Forgery protection

Many sites generate 

1. Session cookies

2. A matching hidden token 

Example : <input type="hidden" name="_csrf" value="abc123">

The server expects BOTH 

• Cookie

• Token 

To match