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Codes and Descriptions of the Most Common Browser Errors

A message code does not necessarily correspond to an error, for example, the numbers 200 to 300 mean that the query has been executed successfully but the results cannot  be displayed in the browser page. The codes 300 to 400 are for redirecting the client, that is, the server informs that you must enter a different URL for the query to be executed successfully. The numbers 400 to 500 are the client’s errors, the numbers 500 to 600 are the server’s errors.

Message Code Description
200 OK The query sent by the client hasb een executed successfully,and its result is in the page header or in the message body.
301 Moved Permanently You’ve accessed a document that had been moved to a different URL.The new address of the documentis indicatedin the“Location” fieldof the page header. Some browsers can not handle this errorcorrectly.
304 Not Modified This message is displayed if the client has queried a document on the server, which had already been saved in the client’s cache,and this document has not been modified on the server since it had last been saved. Then the document is not sent from the server again, and the client must use its local copy. If you cancel file caching on the webserver, this message will not be displayed, and the document will be transmitted from the srver to the client at every query.
400 Bad Request

This is a message about a syntax error in the query detected by the server. Try to correct the error by doing the following.

  1. Clear the cookies and the cache in your browser.
  2. Disable Windows Firewal ltemporarily and repeat the query. If the error does not occur again, it means that the firewall was the cause. Add your browser to the list of authorized programs for the firewall, Make sure the error does not occur any more.
  3. Disable your antivirus software temporarily, reboot and repeat the query that caused the error. If it does not occur any more, configure the antivirus software or change it.
  4. Check your router’s connection and whether it’s operating normally, contact your ISP. If the error occurs from time to time for a reason that is unknown to you, change the Internet Servise Provider.
403 Forbidden

The server informs you that it cannot execute your query because of access restrictions .In most cases, these restrictions are set by the administrator or by the application developer, or are automatically imposed by the web server’s configuration files.This can also mean that the access is prohibited by the security system, or that you do not have sufficient rights to access the file.

More information on the causes of access blocking is contained in the log files of your site or CMS. To display this information in the browser, add the following line: php_flagdisplay_errors on in the .htaccess file that is stored in the root directory of your site

404 Not Found This is a very common error that is displayed in the browser when trying to access a site with a misspelled address. The URL typed in the address bar of your browser does not lead to an existing resource.
413 Request Entity Too Large / 414 Request-URL Too Long

Both messages mean that the server cannot process the query due to its large size: in case of Error 413, this is a query’s body that is too large (for example, a file uploaded), Error 414 is for a URL address.

client_max_body_size 100m;
or the Apache web server, add the lines to the PHP configuration file(php.ini)
post_max_size = 100m
upload_max_filesize = 100m
500 Internal Server Error

This is a message about an internal server errorthat does notcorrespond to the standarderror classes.A white page can be displayed instead of a message. More information onthe causes for theerror that has occurredis containedinthelogfilesontheserver.To display this information in the browser,type the following line php_flagdisplay_errors on in the.htaccess file at is stored inthe root directory of your site.
Then, in casethiserroroccurs,detailed information will be displayedin the browser page.

502 Bad Gateway

Themessagecomes from the server that is agate or a proxy for an upper server.Iftheserverreceivesabadresponsefromthelatter,or does not receive any response at all,an error message is sent to the client:“502BadGateway”.

Make sure that the web services on the upper server have been enabled, andfunction normally.Viewtheerrorlogfileson that web server,reboot theApache/Nginxor any other web server you are using,if required.

503 Service Unavailable

Thisisaservererrorthatoccurs due totemporary problems on theweb services functioning.Forexample,itcanbea restart for technical reasons,a setup of configuration files, etc.If no such actions are being performed,the reasons can be the following:

  • transmitting ofsizeable contentvia the Web(fileloading);
  • CMSpluginsandscriptsthatdonotworkcorrectly:check and remove all the unnecessary components,disable the working pluginsone by oneto find out which of themcauses the error;
  • sendingmail:doitatnightwhen the number of site users is minimum;
  • SQLqueries:optimize the workof the database server(use caching,table indexing,optimize the queries);
  • a great number of concurrent web server queries that occurs due to incorrect organizing of the website pages(each component sends aseparate server query);
  • a great number of users opening the site at the same time;
  • a chat room functioning at the website;indexing bots,scripts,a DDoS attack.
504 Gateway Timeout

Thisisamessagefromtheserverthatisagate or a proxy for an upper server,and has not received anyresponse to its query from the latter.Thetimetowaitforaresponseislimited by the parameter,it can be increased ifasizeable query has to be executed.ForNginx,add the following lines to the configuration file:

proxy_read_timeout 120;
proxy_connect_timeout 120;
This can in its turn increase the server load.
If the parameter modification does not have any impacton the error,and it still remains,the cause may be the lack of resources on the upper server.

None of the Above Has Fixed the Error

Please contact our support service with a detailed description of how the error occured and what actions preceeded it; please help us identify the error faster by attaching screenshots to the inquiry.

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