error: <...> escaping malformed URI reference

Cause:

An URI contains non-authorized characters. Or the quotes around the URI are not closed.

Solution:

Correct the URI.

Samples:

error: <a> escaping malformed URI reference

BAD   <a href="http://www.mozilla.org/one space.html">space</a>
GOOD  <a href="http://www.mozilla.org/one%20space.html">space</a>
GOOD  <a href="http://www.mozilla.org/one+space.html">space</a>

BAD   <a href="http://www.w3c.org>w3c</a>
GOOD  <a href="http://www.w3c.org">w3c</a>

For the first example, a space should not be contained in URL. (Even if it works in all browsers...). This is described in detail in the RFC1738 (Look for Unsafe)

References:

RFC2396 - Uniform Resource Identifiers (URI): Generic Syntax"
RFC1738 - Uniform Resource Locators