400 Bad Request

In This Article

The HTTP 400 Bad Request response status code indicates that the server could not understand the request due to invalid syntax. The client should not repeat this request without modification.

Status

400 Bad Request

Specifications

Specification	Title
RFC 7231, section 6.5.1: 400 Bad Request	Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content

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Contributors to this page: fscholz

Last updated by: fscholz, Feb 24, 2017, 6:39:40 AM

See also

HTTP
Guides:
Resources and URIs
1. Identifying resources on the Web
2. Data URIs
3. Introduction to MIME Types
4. Complete list of MIME Types
5. Choosing between www and non-www URLs
Basics of HTTP
1. Overview of HTTP
2. Evolution of HTTP
3. HTTP Messages
4. A typical HTTP session
5. Connection management in HTTP/1.x
HTTP security
1. Content Security Policy (CSP)
2. HTTP Public Key Pinning (HPKP)
3. HTTP Strict Transport Security (HSTS)
4. Cookie security
5. X-Content-Type-Options
6. X-Frame-Options
7. X-XSS-Protection
8. Mozilla web security guidelines
9. Mozilla Observatory
HTTP access control (CORS)
HTTP authentication
HTTP caching
HTTP compression
HTTP conditional requests
HTTP content negotiation
HTTP cookies
HTTP range requests
HTTP redirects
HTTP specifications
References:
HTTP headers
1. Accept
2. Accept-Charset
3. Accept-Encoding
4. Accept-Language
5. Accept-Ranges
6. Access-Control-Allow-Credentials
7. Access-Control-Allow-Headers
8. Access-Control-Allow-Methods
9. Access-Control-Allow-Origin
10. Access-Control-Expose-Headers
11. Access-Control-Max-Age
12. Access-Control-Request-Headers
13. Access-Control-Request-Method
14. Age
15. Allow
16. Authorization
17. Cache-Control
18. Connection
19. Content-Disposition
20. Content-Encoding
21. Content-Language
22. Content-Length
23. Content-Location
24. Content-Range
25. Content-Security-Policy
26. Content-Security-Policy-Report-Only
27. Content-Type
28. Cookie
29. Cookie2
30. DNT
31. Date
32. ETag
33. Expect
34. Expires
35. Forwarded
36. From
37. Host
38. If-Match
39. If-Modified-Since
40. If-None-Match
41. If-Range
42. If-Unmodified-Since
43. Keep-Alive
44. Large-Allocation
45. Last-Modified
46. Location
47. Origin
48. Pragma
49. Proxy-Authenticate
50. Proxy-Authorization
51. Public-Key-Pins
52. Public-Key-Pins-Report-Only
53. Range
54. Referer
55. Referrer-Policy
56. Retry-After
57. Server
58. Set-Cookie
59. Set-Cookie2
60. Strict-Transport-Security
61. TE
62. Tk
63. Trailer
64. Transfer-Encoding
65. Upgrade-Insecure-Requests
66. User-Agent
67. Vary
68. Via
69. WWW-Authenticate
70. Warning
71. X-Content-Type-Options
72. X-DNS-Prefetch-Control
73. X-Forwarded-For
74. X-Forwarded-Host
75. X-Forwarded-Proto
76. X-Frame-Options
77. X-XSS-Protection
HTTP request methods
1. CONNECT
2. GET
3. HEAD
4. OPTIONS
5. POST
HTTP response status codes
1. 100 Continue
2. 200 OK
3. 201 Created
4. 202 Accepted
5. 204 No Content
6. 206 Partial Content
7. 301 Moved Permanently
8. 302 Found
9. 303 See Other
10. 304 Not Modified
11. 307 Temporary Redirect
12. 308 Permanent Redirect
13. 401 Unauthorized
14. 403 Forbidden
15. 404 Not Found
16. 405 Method Not Allowed
17. 406 Not Acceptable
18. 407 Proxy Authentication Required
19. 410 Gone
20. 412 Precondition Failed
21. 416 Range Not Satisfiable
22. 451 Unavailable For Legal Reasons
23. 500 Internal Server Error
24. 501 Not Implemented
25. 502 Bad Gateway
26. 503 Service Unavailable
27. 504 Gateway Timeout
28. 505 HTTP Version Not Supported
CSP directives
1. CSP: base-uri
2. CSP: block-all-mixed-content
3. CSP: child-src
4. CSP: connect-src
5. CSP: default-src
6. CSP: font-src
7. CSP: form-action
8. CSP: frame-ancestors
9. CSP: frame-src
10. CSP: img-src
11. CSP: manifest-src
12. CSP: media-src
13. CSP: object-src
14. CSP: plugin-types
15. CSP: referrer
16. CSP: report-uri
17. CSP: require-sri-for
18. CSP: sandbox
19. CSP: script-src
20. CSP: style-src
21. CSP: upgrade-insecure-requests
22. CSP: worker-src