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412 Precondition Failed

The HTTP 412 Precondition Failed , . , GET HEAD, If-Unmodified-Since {HTTPHeader("If-None-Match")}} . , , , .

In this article

412 Precondition Failed

RFC 7232, 4.2: 412 Precondition Failed Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests

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  1. HTTP
  3. HTTP
  4. Evolution of HTTP
  5. HTTP
  6. HTTP
  7. MIME types
    1. MIME
  8. Compression in HTTP
  9. HTTP-
  10. HTTP
  11. HTTP-
  12. HTTP
  13. HTTP
  14. Range requests
  15. Client hints
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  17. Compression Dictionary Transport
  18. Network Error Logging
    1. Accept
  20. Browser detection using the UA string
  21. Connection management in HTTP/1.x
  22. Protocol upgrade mechanism
  23. Proxy servers and tunneling
    1. Proxy Auto-Configuration (PAC) file
  24. HTTP
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    2. Practical implementation guides
    3. Feature Policy
    4. Cross-Origin Resource Policy (CORP)
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    6. Fetch metadata
    7. Cross-Origin Resource Sharing (CORS)
    8. CORS
      1. : CORS disabled
      2. : CORS 'Access-Control-Allow-Origin' 'xyz'
      3. : CORS Access-Control-Allow-Origin
      4. Reason: CORS header 'Origin' cannot be added
      5. Reason: CORS preflight channel did not succeed
      6. : CORS
      7. Reason: CORS request external redirect not allowed
      8. Reason: CORS request not HTTP
      9. Reason: Credential is not supported if the CORS header 'Access-Control-Allow-Origin' is '*'
      10. Reason: Did not find method in CORS header 'Access-Control-Allow-Methods'
      11. Reason: expected 'true' in CORS header 'Access-Control-Allow-Credentials'
      12. Reason: invalid token 'xyz' in CORS header 'Access-Control-Allow-Headers'
      13. Reason: invalid token 'xyz' in CORS header 'Access-Control-Allow-Methods'
      14. Reason: missing token 'xyz' in CORS header 'Access-Control-Allow-Headers' from CORS preflight channel
      15. Reason: Multiple CORS header 'Access-Control-Allow-Origin' not allowed
    9. Content Security Policy (CSP)
      1. Errors and warnings
  26. HTTP
    1. Accept
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    24. Authorization
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    64. If-None-Match
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    67. Integrity-Policy
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    69. Keep-Alive
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    71. Link
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    98. Sec-CH-Device-Memory
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    101. Sec-CH-Prefers-Reduced-Motion
    102. Sec-CH-Prefers-Reduced-Transparency
    103. Sec-CH-UA
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    107. Sec-CH-UA-Full-Version
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    111. Sec-CH-UA-Platform
    112. Sec-CH-UA-Platform-Version
    113. Sec-CH-UA-WoW64
    114. Sec-CH-Viewport-Height
    115. Sec-CH-Viewport-Width
    116. Sec-CH-Width
    117. Sec-Fetch-Dest
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    119. Sec-Fetch-Site
    120. Sec-Fetch-Storage-Access
    121. Sec-Fetch-User
    122. Sec-GPC
    123. Sec-Private-State-Token
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    125. Sec-Private-State-Token-Lifetime
    126. Sec-Purpose
    127. Sec-Redemption-Record
    128. Sec-Speculation-Tags
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  28. HTTP
    1. 100 Continue
    2. 101 Switching Protocol
    3. 102 Processing
    4. 103 Early Hints
    5. 200 OK
    6. 201 Created
    7. 202 Accepted
    8. 203 Non-Authoritative Information
    9. 204 No Content
    10. 205 Reset Content
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    12. 207 Multi-Status
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    14. 226 IM Used
    15. 300 Multiple Choices
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    30. 408 Request Timeout
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    33. 411 Length Required
    34. 412 Precondition Failed
    35. 413 Payload Too Large
    36. 414 URI Too Long
    37. 415 Unsupported Media Type
    38. 416 Range Not Satisfiable
    39. 417 Expectation Failed
    40. 418 I'm a teapot
    41. 421 Misdirected Request
    42. 422 Unprocessable Entity
    43. 423 Locked
    44. 424 Failed Dependency
    45. 425 Too Early
    46. 426 Upgrade Required
    47. 428 Precondition Required
    48. 429 Too Many Requests
    49. 431 Request Header Fields Too Large
    50. 451 Unavailable For Legal Reasons
    51. 500 Internal Server Error
    52. 501 Not Implemented
    53. 502 Bad Gateway
    54. 503 Service Unavailable
    55. 504 Gateway Timeout
    56. 505 HTTP Version Not Supported
    57. 506 Variant Also Negotiates
    58. 507 Insufficient Storage
    59. 508 Loop Detected
    60. 510 Not Extended
    61. 511 Network Authentication Required
  29. CSP
    1. base-uri
    2. block-all-mixed-content
    3. child-src
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    15. prefetch-src
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    18. require-trusted-types-for
    19. sandbox
    20. script-src
    21. script-src-attr
    22. script-src-elem
    23. style-src
    24. style-src-attr
    25. style-src-elem
    26. trusted-types
    27. upgrade-insecure-requests
    28. worker-src
  30. Permissions-Policy
    1. accelerometer
    2. ambient-light-sensor
    3. aria-notify
    4. attribution-reporting
    5. autoplay
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    12. cross-origin-isolated
    13. deferred-fetch
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    17. fullscreen
    18. gamepad
    19. geolocation
    20. gyroscope
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    22. identity-credentials-get
    23. idle-detection
    24. language-detector
    25. language-model
    26. local-fonts
    27. local-network
    28. local-network-access
    29. loopback-network
    30. magnetometer
    31. microphone
    32. midi
    33. on-device-speech-recognition
    34. otp-credentials
    35. payment
    36. picture-in-picture
    37. private-state-token-issuance
    38. private-state-token-redemption
    39. publickey-credentials-create
    40. publickey-credentials-get
    41. screen-wake-lock
    42. serial
    43. speaker-selection
    44. storage-access
    45. summarizer
    46. translator
    47. usb
    48. web-share
    49. window-management
    50. xr-spatial-tracking
  31. HTTP resources and specifications
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