Error: Code 304 - When the request header includes an 'if modified since' parameter, this error code will be returned if the file has not changed since that date. Search engine spiders (robots) can generate a lot of these errors.

How to fix the Web Error Code Error 304 Not Modified

This article features error number Code 304, commonly known as Not Modified described as When the request header includes an 'if modified since' parameter, this error code will be returned if the file has not changed since that date. Search engine spiders (robots) can generate a lot of these errors.

About Status Codes

When you receive web error codes, you may either be having client or server issues. The problem could be related to browser or settings that are blocking your connection, or it can be any other issues related to the server you are trying to access.

To explain the problem further, here are some useful information about web error codes, their symptoms, causes and repair methods.

Definitions (Beta)

Here we list some definitions for the words contained in your error, in an attempt to help you understand your problem. This is a work in progress, so sometimes we might define the word incorrectly, so feel free to skip this section!

  • Error code - An error code is a value returned to provide context on why an error occurred
  • File - A block of arbitrary information, or resource for storing information, accessible by the string-based name or path
  • Generate - Any question related to the Generate developer framework and CLI tool should tagged using the `generate` tag
  • Header - This tag is deprecated because it lacks discriminating power
  • Request - A request is a message sent by a source to another object.
  • Search - Questions about search algorithm mechanics and implementation
  • Search engine - A search engine is program that searches documents for specified keywords and returns a list of the documents where the keywords were found.
  • Robots - Questions related to physical robots in general should use this tag
  • Includes - A provision that many programming languages provide to allow functionality defined in one file to be used in another.
  • Parameter - Parameters are a type of variable used in a subroutine to refer to the data provided as input to the subroutine.

Symptoms of Code 304 - Not Modified

Web error codes are also known as http status codes. There are five different classes of http status codes and they always start with the following digits, depending on what kind of error was encountered by the user. These are also the symptoms of the error that the user is experiencing. To explain further, here are the status codes.

3xx: Redirection
This status code is sent back to the client if the user must take additional actions to complete the request. The user either receives a notification that the content is unavailable, temporarily or permanently, or is given a clickable URI to a site where the content being requested is moved. The kind of action users need to take are in bold letters, like the following:
300 - Multiple Choices
301 - Moved Permanently
302 - Found
303 - See Other
304 - Not Modified
305 - Use Proxy
307 - Temporary Redirect

Fix Not Modified (Error Error 304)
(For illustrative purposes only)

Causes of Not Modified - Error 304

3XX codes occur because of certain changes made to the original URI and the need to usher the user to a different URI or some other actions described in the error page.

Repair Methods

There are particular troubleshooting steps for particular Web Error codes. However, there are also generalized repair methods users can perform when faced with these kinds of errors.

If a repair method works for you, please click the upvote button to the left of the answer, this will let other users know which repair method is currently working the best.

Please note: Neither nor it's writers claim responsibility for the results of the actions taken from employing any of the repair methods listed on this page - you complete these steps at your own risk.

up vote 1 down vote accepted
  • There are also times when you manually enter the URL of a site you wish to explore. If you are getting errors after doing this, check the URL you just entered on the address bar if you are indeed accessing the correct address. If not, correct the items you typed incorrectly.
When accessing a site, data gets stored in the browser cache. Sometimes, you have tried fixing a web error but the same message appears on your browser. In such cases, you need to clear your browser cache to get rid of the annoying message. Here are ways to do that in different kinds of browsers:
  • On Google Chrome
    • Open Chrome and click the three dots on the upper right portion of your browser
    • Click More Tools and then Click Clear browsing data.
    • You may choose to delete everything or just a certain browsing period.
    • Check the boxes beside Cookies and other site data and Cached images and files.
    • Finally, click Clear data.
  • On Edge
    • Click the ... it is the rightmost button just beneath the close button.
    • Scroll down and Click Settings.
    • Look for Clear browsing data, and click Choose what to clear button.
    • It will give you option to choose which type of data you want to clear, just put a check mark on the items you want to include, then click Clear.
  • On Mozilla
    • Go to History menu and select Clear Recent History.
    • You may click the Alt button if the menu bar is hidden.
    • You will see a dropdown menu where you can select the period or range you want to delete, click your selection.
    • You can click on Details to choose what to clear, whether it be the entire cache or other items.
    • Once selected, click Clear now and then reboot the browser to let changes take effect.
  • If you want to check log files, you may do so by first ensuring that you are logged into the web server computer as an Administrator.
  • Click Start, then Settings, then click Control Panel.
  • Open Administrator Tools and then double-click Internet Services Manager.
  • Select the website from the list of different served sites.
  • Right click the website and then point your mouse to Properties.
  • Select Website tab and then click Properties. On it, you will see General Properties tab. On the bottom of the window, you may see the location of the log files generated.
  • Open log files using WordPad, any text file viewer or Microsoft Word.
  • Here, you should be able to analyze where you got the errors while accessing a server.
For Windows 7
  • Search for Windows Updates on the search bar.
  • Click enter when it comes up on the search results.
  • Check recent updates and click Uninstall updates on recent dates when the error began happening.
For Windows 8 and Windows 10
  • Press the window key and the letter X simultaneously to open Settings
  • When you get to Windows settings, click Update & Security.
  • Click view installed update history, then Uninstall updates.
  • Sometimes, additional Extensions may give you Web Error Codes.
  • Uninstall Extensions you recently installed by going to your browser settings and then clicking More Tools.
  • You will see extensions than had been installed on your browser, choose the latest addition which you suspected caused the problem you are having.
  • This troubleshooting is normally handled by the site admin. If that is you, then you need to have an understanding of Web server configurations.
  • You may check which web server is running your site by using URL or domain checkers. You just need to enter the site address and analyze the results that you will get.
  • You may also check for broken links by right clicking the webpage and clicking on Inspect. This should give you the code to the site on the right side. You may check each anchor text and see if the links connected to them are still live.
  • You may also check for any unwanted characters on the codes and script by Debug Application Codes and Scripts. If you don't have any idea how to do it, you may check this resource to do that.
  • You may also try to Refresh website. Sometimes, the error you are getting is an old error which has not gone away and a simple refresh by clicking F5 may do the job.
Other languages:

Wie beheben Fehler 304 (Nicht geändert) - Wenn der Anforderungsheader einen Parameter "Wenn geändert seit" enthält, wird dieser Fehlercode zurückgegeben, wenn die Datei seit diesem Datum nicht geändert wurde. Suchmaschinen-Spider (Roboter) können viele dieser Fehler erzeugen.
Come fissare Errore 304 (Non modificato) - Quando l'intestazione della richiesta include un parametro "se modificato da", questo codice di errore verrà restituito se il file non è cambiato da quella data. Gli spider dei motori di ricerca (robot) possono generare molti di questi errori.
Hoe maak je Fout 304 (Niet Gewijzigd) - Als de aanvraagheader een parameter 'indien gewijzigd sinds' bevat, wordt deze foutcode geretourneerd als het bestand sinds die datum niet is gewijzigd. Zoekmachine spiders (robots) kunnen veel van deze fouten genereren.
Comment réparer Erreur 304 (Non modifié) - Lorsque l'en-tête de la requête inclut un paramètre 'si modifié depuis', ce code d'erreur sera renvoyé si le fichier n'a pas changé depuis cette date. Les robots des moteurs de recherche (robots) peuvent générer beaucoup de ces erreurs.
어떻게 고치는 지 오류 304 (수정되지 않음) - 요청 헤더에 'if modifyed since' 매개변수가 포함된 경우 해당 날짜 이후 파일이 변경되지 않은 경우 이 오류 코드가 반환됩니다. 검색 엔진 스파이더(로봇)는 이러한 오류를 많이 생성할 수 있습니다.
Como corrigir o Erro 304 (Não Modificado) - Quando o cabeçalho da solicitação inclui um parâmetro 'se modificado desde', esse código de erro será retornado se o arquivo não tiver sido alterado desde essa data. Aranhas de mecanismo de pesquisa (robôs) podem gerar muitos desses erros.
Hur man åtgärdar Fel 304 (Ej modifierad) - När begäranhuvudet innehåller en "om ändrad sedan" -parameter, returneras denna felkod om filen inte har ändrats sedan det datumet. Sökmotorspindlar (robotar) kan generera många av dessa fel.
Как исправить Ошибка 304 (Не изменено) - Когда заголовок запроса включает параметр «если изменено с», этот код ошибки будет возвращен, если файл не изменился с этой даты. Пауки поисковых систем (роботы) могут генерировать множество таких ошибок.
Jak naprawić Błąd 304 (Niezmodyfikowany) - Gdy nagłówek żądania zawiera parametr „jeśli zmodyfikowano od”, ten kod błędu zostanie zwrócony, jeśli plik nie uległ zmianie od tej daty. Pająki wyszukiwarek (roboty) mogą generować wiele takich błędów.
Cómo arreglar Error 304 (No modificado) - Cuando el encabezado de la solicitud incluye un parámetro "si se modificó desde", este código de error se devolverá si el archivo no ha cambiado desde esa fecha. Las arañas de los motores de búsqueda (robots) pueden generar muchos de estos errores.

The Author About The Author: Phil Hart has been a Microsoft Community Contributor since 2010. With a current point score over 100,000, they've contributed more than 3000 answers in the Microsoft Support forums and have created almost 200 new help articles in the Technet Wiki.

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30/11/23 08:48 : A Windows 10 user voted that repair method 3 worked for them.

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