I have the same error on LOCALHOST, and also with windows. (my forum hosted on web works :) )
(thierry is the name of my computer, and is synonyme of "localhost")
link I click on to activate my template is such : (there are 2 "\")
http://thierry/forum/bb-admin/themes.php?theme=D%3A%5C%5CMes+Documents%5C%5Csites_web%5C%5C2diabolos.com%5C%5Cforum%2Fmy-templates%2F2diabolos%2F&_wpnonce=0ecdd913e2
I tried the "patch_to_url_2" in vain.
a "brillant" idea made me change the themes.php :
if ( !in_array($activetheme, $themes) ) {
$activetheme = BBPATH . 'my-templates/2diabolos/'; // THIS LINE WAS 'bb-templates/kakumei/' ...
bb_update_option( 'bb_active_theme', $activetheme );
remove_action( 'bb_admin_notices', $theme_notice );
bb_admin_notice( __('Theme not found. Default theme applied.'), 'error' );
}
works well (hopefully)
(after reflection, I think the following line don't help)
I tried to debug a little bit. I put in themes.php
print_r($themes);
echo "<br>";
echo "the theme you want to activate : " . $_GET['activated'] ;
the result for the first line is good, the "$_GET['activated'] " is empty.