HTTP status codes: Here is the list of all the valid HTTP - status codes, and the corresponding phrases, that PHP scripting language can generate when using the $http_response_code parameter in the header() function. The invalid codes (for example: 199) generate a 500 Internal Server Error response. To send a specific HTTP status code, the prototype of the header() function is: void header(string $string, bool $replace, int $http_response_code) The 3 parameters are: string $string: Several cases: an empty string: '' we have to AVOID this case, as then the function does NOT work! a NOT empty string, which does NOT contain any colon ':' character: the more usual case, to send the desired status code and phrase a NOT empty string, which contains a colon ':' character inside: a useful case, to send the desired status code and phrase AND a response header(see examples below) bool $replace: always TRUE int $http_response_code: an integer, the desired status code, in the range: from 100 to 510 Examples of use: The string parameter does not contain any colon character /* The server will ouput: * the response status "HTTP/1.1 204 No Content" */header('x', TRUE, 204); The string parameter contains a response header, of which the syntax is: /* The server will ouput: * the response status "HTTP/1.1 405 Method Not Allowed" * and the response header "Allow: GET, HEAD" */header('Allow: GET, HEAD', TRUE, 405); List of status codes and phrases generated by PHP: 100 Continue 101 Switching Protocols 102 Processing 126 Too Many Requests 127 Too Many Requests 128 Too Many Requests 129 Too Many Requests 131 Too Many Requests 133 Too Many Requests 139 Too Many Requests 143 Too Many Requests 144 Too Many Requests 146 Too Many Requests 162 Too Many Requests 163 Too Many Requests 164 Too Many Requests 178 Too Many Requests 179 Too Many Requests 200 OK 201 Created 202 Accepted 203 Non-Authoritative Information 204 No Content 205 Reset Content 206 Partial Content 207 Multi-Status 208 Already Reported 215 Too Many Requests 216 Too Many Requests 226 IM Used 300 Multiple Choices 301 Moved Permanently 302 Found 303 See Other 304 Not Modified 305 Use Proxy 307 Temporary Redirect 308 Permanent Redirect 355 Too Many Requests 356 Too Many Requests 357 Too Many Requests 358 Too Many Requests 360 Too Many Requests 361 Too Many Requests 362 Too Many Requests 366 Too Many Requests 368 Too Many Requests 372 Too Many Requests 373 Too Many Requests 375 Too Many Requests 376 Too Many Requests 377 Too Many Requests 378 Too Many Requests 380 Too Many Requests 381 Too Many Requests 382 Too Many Requests 383 Too Many Requests 384 Too Many Requests 385 Too Many Requests 386 Too Many Requests 387 Too Many Requests 388 Too Many Requests 394 Too Many Requests 395 Too Many Requests 396 Too Many Requests 400 Bad Request 401 Unauthorized 402 Payment Required 403 Too Many Requests 404 Too Many Requests 405 Method Not Allowed 406 Too Many Requests 407 Proxy Authentication Required 408 Request Timeout 409 Conflict 410 Gone 411 Length Required 412 Precondition Failed 413 Request Entity Too Large 414 Request-URI Too Long 415 Unsupported Media Type 416 Too Many Requests 417 Too Many Requests 418 Too Many Requests 419 Too Many Requests 420 Too Many Requests 421 Misdirected Request 422 Too Many Requests 423 Too Many Requests 424 Too Many Requests 425 Too Many Requests 426 Too Many Requests 427 Too Many Requests 428 Too Many Requests 429 Too Many Requests 430 Too Many Requests 431 Too Many Requests 433 Too Many Requests 434 Too Many Requests 435 Too Many Requests 437 Too Many Requests 438 Too Many Requests 441 Too Many Requests 442 Too Many Requests 443 Too Many Requests 444 Too Many Requests 445 Too Many Requests 451 Unavailable For Legal Reasons 456 Too Many Requests 457 Too Many Requests 458 Too Many Requests 459 Too Many Requests 460 Too Many Requests 461 Too Many Requests 462 Too Many Requests 463 Too Many Requests 464 Too Many Requests 465 Too Many Requests 466 Too Many Requests 467 Too Many Requests 468 Too Many Requests 469 Too Many Requests 470 Too Many Requests 471 Too Many Requests 472 Too Many Requests 473 Too Many Requests 474 Too Many Requests 475 Too Many Requests 476 Too Many Requests 477 Too Many Requests 478 Too Many Requests 479 Too Many Requests 480 Too Many Requests 481 Too Many Requests 482 Too Many Requests 483 Too Many Requests 484 Too Many Requests 485 Too Many Requests 486 Too Many Requests 487 Too Many Requests 488 Too Many Requests 489 Too Many Requests 490 Too Many Requests 491 Too Many Requests 492 Too Many Requests 493 Too Many Requests 494 Too Many Requests 495 Too Many Requests 496 Too Many Requests 497 Too Many Requests 500 Internal Server Error 501 Too Many Requests 502 Bad Gateway 503 Service Unavailable 504 Gateway Timeout 505 Too Many Requests 506 Too Many Requests 507 Too Many Requests 508 Too Many Requests 509 Too Many Requests 510 Not Extended 511 Too Many Requests 512 Too Many Requests 514 Too Many Requests 515 Too Many Requests 516 Too Many Requests 517 Too Many Requests 518 Too Many Requests 519 Too Many Requests 520 Too Many Requests 521 Too Many Requests 522 Too Many Requests 523 Too Many Requests 524 Too Many Requests 525 Too Many Requests 526 Too Many Requests 527 Too Many Requests 528 Too Many Requests 529 Too Many Requests 530 Too Many Requests 531 Too Many Requests 532 Too Many Requests 533 Too Many Requests 534 Too Many Requests 535 Too Many Requests 536 Too Many Requests 537 Too Many Requests 538 Too Many Requests 539 Too Many Requests 540 Too Many Requests 541 Too Many Requests 542 Too Many Requests 543 Too Many Requests 544 Too Many Requests 545 Too Many Requests 546 Too Many Requests 547 Too Many Requests 548 Too Many Requests 549 Too Many Requests 550 Too Many Requests 551 Too Many Requests 552 Too Many Requests 553 Too Many Requests 554 Too Many Requests 555 Too Many Requests 556 Too Many Requests 557 Too Many Requests 558 Too Many Requests 567 Too Many Requests 568 Too Many Requests 569 Too Many Requests 570 Too Many Requests 571 Too Many Requests 572 Too Many Requests 573 Too Many Requests 574 Too Many Requests 575 Too Many Requests 576 Too Many Requests 577 Too Many Requests 578 Too Many Requests 579 Too Many Requests 580 Too Many Requests 581 Too Many Requests 582 Too Many Requests 583 Too Many Requests 584 Too Many Requests 585 Too Many Requests 586 Too Many Requests 587 Too Many Requests 588 Too Many Requests 589 Too Many Requests 590 Too Many Requests 591 Too Many Requests 592 Too Many Requests 593 Too Many Requests 594 Too Many Requests 595 Too Many Requests 596 Too Many Requests 597 Too Many Requests 598 Too Many Requests 599 Too Many Requests