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The Internet Explorer error “Address not valid”: “The address is not valid”

In this Internet Explorer error message, “address” refers to the whole Uniform Resource Locator (URL) (e.g. http:///www.example.com/foo.html) rather than to a domain name (e.g. www.example.com)¹, which is often just one part of the URL.

This is often caused by an invalid character in the URL. Internet Explorer tries to correct invalid characters (e.g. replacing backward slashes, “\”, with forward slashes “/”), and will include three forward slashes near the beginning of the address if it seems invalid, e.g.

http:`//www.example.com turns into http:///www.example.com

and

http://?www.example.com turns into http:///?www.example.com

Symptoms

Address not valid: The address is not valid

Solutions

The set of characters that are valid depends in a complicated way on their position in the URL (see RFC 3986 for details), but usually a valid URL will:

Start with http://
Be followed by a domain name consisting of letters or numbers, separated by dots
Optionally be followed by at most one of each of the following, in this order:
1. A slash “/”, followed by a file pathname
2. A question mark, followed by a query
3. A number sign “#” followed by an alphanumeric string

Check that the address that you used did not include other characters.

Characters other than letters, digits, underscores and hyphens are often shown using percent encoding in which single characters are represented by a percent symbol followed by two hexadecimal digits, e.g. a space character should be encoded as “%20”

What worked for other people

Other people fixed this error after determining that it was caused by

spyware on their computer in particular browser hijackers
malformed proxy information

Extra information

Uniform Resource Locators (URLs)

The proper structure of a URL is defined in RFC 3986:

scheme “:” authority path [ “?” query ] [ “#” fragment ]
e.g. http://rfc-editor.org/cgi-bin/rfcsearch.pl?searchwords=http&num=25

The scheme: (e.g. “http”) defines the format for the remainder of the URL, with the most common schemes being http, https, mailto, ftp and file.
The authority: (e.g. “rfc-editor.org”) identifies the authority that controls the names used in the remainder of the URL, and is usually the name of a web site.
The path: (e.g. “/cgi-bin/rfcsearch.pl”) identifies the object of interest within the authority, e.g. it often identifies the directories and filename of an object on a web server. It may distinguish between uppercase and lowercase versions of letters when the filesystem is case sensitive. The path is hierarchical, whereas the query is non-hierarchical.
The query: (e.g. “?searchwords=http&num=25”) is optional and can provide non-hierarchical information to supplement the path in identifying an object to be accessed. It is often used to provide search terms or to specify options.
The fragment: is optional and does not appear in the example above. It identifies a particular part of the object on the server. e.g. this part of this web page which describes URLs can be identified with http://www.getnetgoing.com/Internet-Explorer-The-address-is-not-valid.html#url

URLs can also include other elements, such as port numbers and usernames/passwords, as specified in RFC 3986.

Related symptoms

Errors in the address can also lead to Internet Explorer showing a dialog box with the title “Address Bar” and containing a message like:

Windows cannot find 'http://%www.example.com/'. Check the spelling and try again.

Footnotes

¹ Problems with the domain name of a web site lead to the error Internet Explorer cannot display the webpage