Error Messages

400 Bad File Request	Usually means the syntax used in the URL is incorrect (e.g., uppercase letter should be lowercase letter; wrong punctuation marks).
401 Unauthorized	Server is looking for some encryption key from the client and is not getting it. Also, wrong password may have been entered. Try it again, paying close attention to case sensitivity.
403 Forbidden/Access Denied	Similar to 401; special permission needed to access the site -- a password and/or username if it is a registration issue. Other times you may not have the proper permissions set up on the server or the site's administrator just doesn't want you to be able to access the site.
404 File Not Found	Server cannot find the file you requested. File has either been moved or deleted, or you entered the wrong URL or document name. Look at the URL. If a word looks misspelled, then correct it and try it again. If that doesn't work backtrack by deleting information between each backslash, until you come to a page on that site that isn't a 404. From there you may be able to find the page you're looking for.
408 Request Timeout	Client stopped the request before the server finished retrieving it. A user will either hit the stop button, close the browser, or click on a link before the page loads. Usually occurs when servers are slow or file sizes are large.
500 Internal Error	Couldn't retrieve the HTML document because of server-configuration problems. Contact site administrator.
501 Not Implemented	Web server doesn't support a requested feature.
502 Service Temporarily Overloaded	Server congestion; too many connections; high traffic. Keep trying until the page loads.
503 Service Unavailable	Server busy, site may have moved ,or you lost your dial-up Internet connection.
Connection Refused by Host	Either you do not have permission to access the site or your password is incorrect.
File Contains No Data	Page is there but is not showing anything. Error occurs in the document. Attributed to bad table formatting, or stripped header information.
Bad File Request	Browser may not support the form or other coding you're trying to access.
Failed DNS Lookup	The Domain Name Server can't translate your domain request into a valid Internet address. Server may be busy or down, or incorrect URL was entered.
Host Unavailable	Host server down. Hit reload or go to the site later.
Unable to Locate Host	Host server is down, Internet connection is lost, or URL typed incorrectly.
Network Connection Refused by the Server	The Web server is busy.

FTP Error Codes

500 Series:

The command was not accepted and the requested action did not take place.

500 Syntax error, command unrecognized. This may include errors such as command line too long.
501 Syntax error in parameters or arguments.
502 Command not implemented.
503 Bad sequence of commands.
504 Command not implemented for that parameter.
530 Not logged in.

532 Need account for storing files.
550 Requested action not taken. File unavailable (e.g., file not found, no access).
551 Requested action aborted. Page type unknown.
552 Requested file action aborted. Exceeded storage allocation (for current directory or dataset).
553 Requested action not taken. File name not allowed.

400 Series:

The command was not accepted and the requested action did not take place, but the error condition is temporary and the action may be requested again.

421 Service not available, closing control connection. This may be a reply to any command if the service knows it must shut down.
425 Can't open data connection.
426 Connection closed; transfer aborted.
450 Requested file action not taken.
451 Requested action aborted. Local error in processing.
452 Requested action not taken. Insufficient storage space in system.File unavailable (e.g., file busy).

300 Series:

The command has been accepted, but the requested action is dormant, pending receipt of further information.

331 User name okay, need password.
332 Need account for login.
350 Requested file action pending further information

200 Series:

The requested action has been successfully completed.

200 Command okay.
202 Command not implemented, superfluous at this site.
211 System status, or system help reply.
212 Directory status.
213 File status.
214 Help message. On how to use the server or the meaning of a particular non-standard command. This reply is useful only to the human user.
215 NAME system type. Where NAME is an official system name from the list in the Assigned Numbers document.
220 Service ready for new user.
221 Service closing control connection.
225 Data connection open; no transfer in progress.
226 Closing data connection. Requested file action successful (for example, file transfer or file abort).
227 Entering Passive Mode (h1,h2,h3,h4,p1,p2).
230 User logged in, proceed. Logged out if appropriate.
250 Requested file action okay, completed.
257 "PATHNAME" created.

100 Series:

The requested action is being initiated, expect another reply before proceeding with a new command.

110 Restart marker reply. In this case, the text is exact and not left to the particular implementation; it must read: MARK yyyy = mmmm where yyyy is User-process data stream marker, and mmmm server's equivalent marker (note the spaces between markers and "=").
120 Service ready in nnn minutes.
125 Data connection already open; transfer starting.
150 File status okay; about to open data connection