Check for broken links here: Link Checker
Note: The term URL stands for Universal Resource Location - for example the actual address of a webpage - whereas URI stands for Universal Resource Identifier, meaning the name of a particular resource. Although the two terms are frequently used interchangeably, they are semantically distinct.Timeout
The server did not respond to the URL request within the allotted time.
Redirection Loop / Too Many Redirections
The URL results in a redirection (e.g. 301 or 302) either back to itself, or to a chain of redirections which either eventually reaches the original URL or appears to be endless. Note that redirections sometimes depend on whether cookies are enabled.
The page was served in an unexpected compressed format. When the scanner requests pages, it sets a value in the request header to tell the remote server to send the page as uncompressed text. Despite this header value, some sites return data compressed using the BR format, which the link checker is unable to decompress. The fact that some data was returned is a reasonable indication that the URL is valid, even if it is not strictly behaving correctly - however the page will not have been scanned for further links.