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HTTP Error 503 - Service unavailable

Introduction

The Web server (running the Web site) is currently unable to handle the HTTP request due to a temporary overloading or maintenance of the server. The implication is that this is a temporary condition which will be alleviated after some delay. Some servers in this state may also simply refuse the socket connection, in which case a different error may be generated because the socket creation timed out.

Fixing 503 errors

The Web server is effectively 'closed for repair'. It is still functioning minimally because it can at least respond with a 503 status code, but full service is impossible i.e. the Web site is simply unavailable. There are a myriad possible reasons for this, but generally it is because of some human intervention by the operators of the Web server machine. You can usually expect that someone is working on the problem, and normal service will resume as soon as possible.

Please contact the system operators of the Web site (e.g. your ISP) to determine why the service is down. They will be in a much better position to help you than we are for this type of error.

503 errors in the HTTP cycle

Any client (e.g. your Web browser or our CheckUpDown robot) goes through the following cycle when it communicates with the Web server:

  1. Obtain an IP address from the IP name of the site (the site URL without the leading 'http://'). This lookup (conversion of IP name to IP address) is provided by domain name servers (DNSs).
  2. Open an IP socket connection to that IP address.
  3. Write an HTTP data stream through that socket.
  4. Receive an HTTP data stream back from the Web server in response. This data stream contains status codes whose values are determined by the HTTP protocol. Parse this data stream for status codes and other useful information.

This error occurs in the final step above when the client receives an HTTP status code that it recognises as '503'.

Most Common HTTP Errors

403 - Forbidden
404 - Not Found
500 - Internal Server Error
502 - Bad Gateway
503 - Service Unavailable

Other HTTP Errors

This link contains an overview and a list of other HTTP Errors

For quick access to other errors, use the links below:
300 Error Range: 300 301 302 303 304 305 306 307
400 Error Range: 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417
500 Error Range: 500 501 502 503 504 505

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