I am using wordpress latest version.
Currently my blog is set to custom permalink /index.php/%postname%/
http://abc.com/blog/index.php
(working fine)
but when click on NEXT button to go to page 2, it fail.
It suppose to go to http://abc.com/blog/index.php/page/2/
But it go to http://abc.com/blog/index.php/Index.php/page/2/
(an extra /Index.php/ is being added....)
This happen only to page 2. At page 2 go to page 3 onwards, the url is working properly.
It is very easy to fix.
Just put a line at clean_url() function in wp-includes/formatting.php:
$url = str_replace('index.php/Index.php','index.php',$url);
just give this line at the beginning of the function before any "if Statements"