Notice: ... discarding newline in URI reference

Cause:

The URL given in the tag is containing newline or carriage return. This is a notice, not a real HTML error.

Example:

<a> discarding newline in URI reference.

Good<a href="my_link
.html">my link</a>
Good<a href="my_link.html">
my_link</a>

Solution:

Remove the newline in the URL

References: