Bittorrent Tutorials

Decoding and dealing with browser error messages

"The sad thing about Unix is that no matter how many times you hit yourself over the head with it, you never quite manage to lose conciousness."

If you've ever stumbled over cryptic browser messages such as 400: Bad request or 404: Not found you may appreciate some of the hostility that is directed towards Unix, the operating system upon which most of the World Wide Web was built. Unix is so opaque it makes DOS seem warm and cuddly.

Mostly, this lack of user friendliness doesn't matter as it remains hidden from the average Internet user. But if you come face to face with any of those not-so-rare Internet error messages which somehow make you feel as if you're to blame, you're going to need some Unix-to-human translation to understand what's gone wrong. So, here it is...

400: Bad request

The address you typed is somehow incorrect. The URL may not exist or you may not have authority to access the document on the server.

How to handle it: Check that you typed the URL correctly. Remember that Internet addresses are case sensitive, so is not the same as (although sometimes sites will redirect requests for one URL which uses mixed case to another URL which has only lowercase). If you're not used to typing URLs, it's very easy to leave out the correct punctuation or to substitute a slosh (\) for a slash (/). Computers are very finicky about this stuff.

If you're trying an address you found elsewhere – perhaps in a magazine or on a Web site – it's possible the original author got it wrong. You might want to check the capitalisation or try just the first part of the address. For instance, if you can't get to, try by itself, and then see if you can manually navigate to the Holidays page.

401: Unauthorised

You're treading on restricted ground. The page you've tried to access is only available to people authorised by the host or those with the correct password. Sites can also restrict access to those people who are connecting from a particular domain: for instance, you might only be able to access a site if you connect via a .edu or .gov domain or via a particular country domain.

How to handle it: If you know you should have access to the site, check the spelling of your password, including the case. If you still have no success, contact the site administrator to see whether there's a problem with your logon ID or password.

403: Forbidden

This is very like 401. The page you're trying to view is password protected or restricted in some other way.

How to handle it: If you have the password for the site, check the spelling. If you still can't get in, you may need to e-mail the site's Webmaster.

404: Not found

The particular page you're looking for can't be found on the server. It may be that the page no longer exists (remember, the Web is a very volatile place and no page lives forever) or that it's been moved to another location or renamed.

How to handle it: Once again, check the spelling of the URL. You can also try going up one or more levels and seeing if you can locate the page that way. For instance, if you're looking for and can't seem to find it, try and, if that doesn't help, try and finally Once you manage to load a page, you can then try navigating your way to the page or using the site's search facility, if it has one, to locate the page you want.

geekgirl.technote: Custom-designed error pages
Because the standard error messages Web servers provide are usually difficult to comprehend, many Web site owners create their own hand-crafted error pages. Such pages most commonly pop up in place of the 404: Not found message, but sometimes in the place of other messages, too.

Most Web designers try to make their messages more informative and helpful than the standard messages, although some use the occasion to have a little fun. Check out Area 404 at the 404 Research Lab to see a whole pile of examples and to learn how to do the trick on your own Web site.

I use a customised 404: Not found page on geekgirl's, too. You'll come across the page anytime you mistype an address on the site, or any time I've let a link get out of date. To try it out now, just type an address to a non-existent page -- such as -- in your browser's address box and see what happens. You should see the page illustrated below. Note that this customised page provides a whole lot more information, plus a choice of options to help you track down the missing content.'s replacement 'not found' page

500: Internal Error

There's something wrong at the Web site itself. As their server is not functioning correctly, it's unable to provide you with the requested Web page.

How to handle it: Contact the site's Webmaster or administrator, or try again later in the hopes that they have noticed the problem and fixed it themselves.

502: Bad gateway

The server from which you tried to access a document needed to obtain that document from another server, and received an error message from that server in the process.

How to handle it: There's not too much you can do about this apart from trying again later.

503: Service unavailable

This is a "temporarily out of order" sign, and it's sometimes reported as Gateway timeout. It means either the server that hosts the site is currently not working or is unavailable, your ISP's server is down, or your own system or company Internet gateway (if you're on a LAN) is not working.

How to handle it: Wait a minute and try again. If you get the message for a lengthy period or with every attempt to connect to any site, check that your PC and LAN connections are functioning, and then check with your ISP or the remote site. This may entail a phone call to their tech support line.

Bad file request

You've requested a page that contains a form with a feature your browser can't support.

How to handle it: Let the Webmaster know the form is unusable.

Connection refused by host

Like the Forbidden and Unauthorised messages, this one usually means you've tried to access a password-protected site or one that's restricted to users from particular domains.

How to handle it: If you have the password, check that you typed it correctly and try again. If it still won't work, contact the Webmaster.

Failed DNS lookup

You've typed a URL that can't be converted into a valid Internet address.

The 'DNS' in this message stands for domain name system (or service). Addresses on the Internet take the form of a string of numbers. For instance, is the domain name of this Web site; is its Internet address. Because we, as humans, tend to handle names more easily than strings of numbers, we type in the domain name, which is looked up in a table and matched to its corresponding, computer-friendly, Internet address. In the case of a failed DNS lookup, the domain name can't be found in the table.

How to handle it: Check that you typed the URL correctly. If you did, wait a few seconds and try again.

File contains no data

You've connected to a server that doesn't have any Web documents on it.

How to handle it: Try the URL once more. If you still get the same message, try again later: it may be that you've stumbled onto the site just as it's being updated.

Host unavailable

The site's server is currently down.

How to handle it: Try again a few times. If you still can't get in, the site may be down for maintenance. Try again later.

Host unknown

It could be that the site's server is down (as with the previous message) or that your modem lost the connection.

How to handle it: First try reaccessing the site by hitting the Reload button. Make sure you've typed the URL correctly and that you're still online.

Network connection was refused by the server

This usually means you've come across an overworked server that can't handle any more users. This is the message you get if the server hasn't been set up to display the more informative "Service temporarily overloaded" message.

How to handle it: Try again. If you still don't get on, be patient and try again later.

NNTP server error

This is a Usenet newsgroup error message. You'll come across it when you're trying to join a newsgroup but can't get access.

How to handle it: First, make sure you typed the newsgroup address correctly. If you did, try again later. If you still can't get on, it may be that your ISP doesn't provide access to that particular newsgroup – you'll need to contact your ISP to find out and, perhaps, complain about its absence.

Permission denied

This is an FTP message which you'll see if you try to upload a file to an FTP site and the site administrator doesn't want you to. You may also see it if you try to download a file using the wrong syntax or simply when the site is to busy to handle an upload.

How to handle it: Check that you're using the correct syntax. If so, try again later. If you still can't upload the file, contact the site's administrator.

Server returned extended information

This one usually pops up when you try to access a file download or file download site that's very busy.

How to handle it: While the browser message is not very informative, if you're using an FTP program you'll probably see the much more informative "There are too many anonymous FTP users using the site at this time. Please try again in a few minutes." That's exactly what you should do.

Too many connections – try again later

You're trying to access a site that's already overwhelmed with visitors.

How to handle it: Try again a few times and, if you still can't get in, try again later.

Too many users

This is the FTP equivalent of the Too many connections message. FTP sites allow a certain number of anonymous connections at any one time. If you try to log on when that limit is reached, you'll receive this message.

How to handle it: Keep on trying. Remember, some of the really big download sites, such as Tucows, have mirror sites elsewhere which make the same files available. If you are locked out of the main site by heavy traffic, see if you can find a mirror site to use.

Unable to locate host

This is similar to the Host unknown message. It means the site's server is unavailable at the moment, or that you've lost the modem connection.

How to handle it: Check the spelling of the URL and click Reload to see if you can get through. If not, make sure you're online. You may need to wait and try later.

Unable to locate the server

The particular server where the site is located cannot be found – either it no longer exists or you've got the URL wrong.

How to handle it: Check your spelling.

You can't log on as an anonymous user

This is a message from an FTP site. Either the site doesn't provide anonymous access, or it's reached its limit for anonymous users.

How to handle it: Try again later. If you're using your browser to access the FTP site, make sure you've configured it correctly: most FTP sites require an ID of anonymous and your e-mail address as the password.

Helper application not found or Viewer not found

Most browsers require additional programs to 'view' files such as sound clips, video, 3D VRML pages, Zip (compressed) files, spreadsheets and so on.

How to handle it: The latest versions of the major browsers usually offer to install the required 'viewer' or 'helper' program automatically. If you want to view the file, click OK to install the program and follow the prompts. If your browser doesn't prompt you for automatic installation, you'll usually find the error message provides information about the type of file that can't be viewed. Look for a reference to graphic, VRML, audio and so on.

Most sites will provide a link to another site where you can download a viewer. Alternatively, try out Netscape's extensive list of plug-ins (there are almost 200 plug-ins available) and its guide to configuring helper applications.

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