Core: escaping of chars not allowed in URIs per RFC 3986. Per RFC 3986 only the following characters are allowed in URIs unescaped: unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~" gen-delims = ":" / "/" / "?" / "#" / "[" / "]" / "@" sub-delims = "!" / "$" / "&" / "'" / "(" / ")" / "*" / "+" / "," / ";" / "=" And "%" can appear as a part of escaping itself. The following characters are not allowed and need to be escaped: %00-%1F, %7F-%FF, " ", """, "<", ">", "\", "^", "`", "{", "|", "}". Not escaping ">" is known to cause problems at least with MS Exchange (see http://nginx.org/pipermail/nginx-ru/2010-January/031261.html) and in Tomcat (ticket #2191). The patch adds escaping of the following chars in all URI parts: """, "<", ">", "\", "^", "`", "{", "|", "}". Note that comments are mostly preserved to outline important characters being escaped.