Answers.Body: <p>Add this to your nginx <code>server</code> block:</p>
  
  <pre><code>server {
    ...
    large_client_header_buffers 4 16k;
    ...
  } 
  </code></pre>
  
  <p>and restart nginx. The default is 8k. If you have a lot of headers, beefing that value up should resolve it otherwise you may want to play with <a href="http://nginx.org/en/docs/http/ngx_http_core_module.html#client_header_buffer_size" rel="nofollow"><code>client_header_buffer_size</code></a> as well.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2016-01-14T19:57:04.770Z
Answers.Text: FWIW I encountered the exact same problem a few months back and this is precisely what fixed it. 'Twas tricky because it only occurred in production, where there was lots of tracking garbage and many a cookie involved.
Answers.UserDisplayName: Matt Stein
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2016-01-15T10:12:53.213Z
Answers.Text: Thanks very much, not seen this before but again it's only on staging (not local or live!). Fixed the issue perfectly :)
Answers.UserDisplayName: Chris Southam
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2016-01-15T20:50:09.907Z
Answers.Text: Good deal! nginx is fun but its docs can be lacking ;)
Answers.UserDisplayName: RitterKnight
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2016-01-14T18:20:36.697Z
Answers.LastActivityDate: 2016-01-14T18:29:45.477Z
Answers.LastEditDate: 2016-01-14T18:29:45.477Z
Answers.UserDisplayName: RitterKnight
Body: <p>On attempting to login into either a front-end account or admin account I'm hit by:</p>
  
  <p>400 Bad Request<br>
  Request Header Or Cookie Too Large<br>
  nginx/1.8.0</p>
  
  <p>It's only happened recently but running the latest Craft CMS v2.5.2757 and from looking at the cookies created during login I think it's possibly related to CSRF protection as deleting the top cookie in the list below fixes the issue until you log in again.</p>
  
  <p><a href="https://i.sstatic.net/DPjKR.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/DPjKR.png" alt="Google Console Log"></a></p>
  
  <p>Running a few other Craft sites on the same staging nGinx server without the same issue, and even the same codebase is running another site without issue.</p>
  
  <p>Any thoughts please?!</p>
  
Tags: <nginx>
Title: 400 Bad Request on account or admin login
ThreadText: # 400 Bad Request on account or admin login
  
  (Asked by: username_0 on 2016-01-14)
  
  On attempting to login into either a front-end account or admin account I'm hit by:
  
  400 Bad Request  
  Request Header Or Cookie Too Large  
  nginx/1.8.0
  
  It's only happened recently but running the latest Craft CMS v2.5.2757 and from looking at the cookies created during login I think it's possibly related to CSRF protection as deleting the top cookie in the list below fixes the issue until you log in again.
  
  [![Google Console Log](https://i.sstatic.net/DPjKR.png)](https://i.sstatic.net/DPjKR.png)
  
  Running a few other Craft sites on the same staging nGinx server without the same issue, and even the same codebase is running another site without issue.
  
  Any thoughts please?!
  
  **Tags:** nginx
  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2016-01-14. Score: 3 | Accepted answer
  
  Add this to your nginx `server` block:
  
  ```
  server {
    ...
    large_client_header_buffers 4 16k;
    ...
  } 
  
  ```
  
  and restart nginx. The default is 8k. If you have a lot of headers, beefing that value up should resolve it otherwise you may want to play with [`client_header_buffer_size`](http://nginx.org/en/docs/http/ngx_http_core_module.html#client_header_buffer_size) as well.
  
  > **Comments:**
  > **username_2**: FWIW I encountered the exact same problem a few months back and this is precisely what fixed it. 'Twas tricky because it only occurred in production, where there was lots of tracking garbage and many a cookie involved.  
  > **username_0**: Thanks very much, not seen this before but again it's only on staging (not local or live!). Fixed the issue perfectly :)  
  > **username_1**: Good deal! nginx is fun but its docs can be lacking ;)  
  
  ---
  
  