What does 404 Not Found and other web page errors mean?

The most common mistakes

Error 401 Unauthorized

This error occurs due to authorization issues. Most often, this can be fixed by re-entering your account on the home page of the site.

If re-authorization did not help, look for the problem yourself. But it is also impossible to exclude problems with the server on which the site is located, although they are unlikely.

Error 403 Forbidden

This error occurs when a user is logged in to the site, but for some reason cannot access some pages or files. Most often, this means that he does not have permission to view the published content. It is also possible that the page is simply closed to all users. For example, Apache servers restrict access to the filesystem directory.

Error 404 Not Found

One of the most common mistakes. It means that the server cannot find anything at the address specified in the request. In this case, either you enter the URL incorrectly, or you come across a broken link that leads to a non-existent page. There is also a possibility that the page has been moved, and the browser is accessing the server at the old address.

Usually, site owners try to soften the user's anger when he sees this error. There are many examples of cool 404 error pages on the Web.

Error 504 Gateway Timeout

This error occurs when the server fails to respond within the specified time. Most often this happens due to the heavy load: requests do not have time to be processed. It could also be any other server-side problem. All you can do is try to visit the site again after a while.

What to do if the browser throws an error

If the 504 error indicates problems on the server, then 4xx class errors most often appear due to the user's fault. If you are logged into the site or enter the correct URL, but the error pages continue to open, try clearing the cache or cookie in your browser.

Delete cookie

Cookies are small pieces of data. They contain various information received from the web server, including the authorization of the user on the site.

Chrome

For individual sites:

Go to "Settings" → "Advanced"

Select Content Settings → Cookies → All Cookies and Site Data

Remove all cookies:

Go to "Settings" → "Advanced".
Scroll down to the "Clear history" item.

Select "Cookies and other site data" to clear

Yandex browser

For individual sites:

Go to "Settings" → "Advanced"

Error 404. Deleting cookies in Yandex Browser

Select Content Settings → Show Cookies and Site Data

Remove all cookies:

Go to "Settings" → "Advanced".
Select "Clear download history" → "Cookies and other site data".

Firefox

Go to Settings → Privacy & Security.
Click on "Show cookies".

Choose what you want to do: delete files for individual sites or all cookies

Opera

Go to "Settings" → "Security".
Open All Cookies and Site Data.

Choose whether to delete individual site files or all cookies

Safari

Go to "Settings" → "Privacy".
Click on "Manage Site Data".
Choose what to do: delete the data of individual sites or clear everything.

Clear browser cache

The cache contains data about visited web pages. It happens that some changes have occurred on the site, and the browser continues to access the old data.