CGI Error from changing permalinks

Hi,

Have a check with this:

1) If your blog is running on PHP 5.X version then downgrate it to PHP 4.x version.
2) Check log permissions in /wp-includes/wp-db.php file and open file and replace the code as mentioned below:

In wp-db.php around line 163 find the following code:
error_log($error_str, 0)

Replace it as this:

//ORIGINAL CODE: error_log($error_str, 0);

Upload the file and check the website.

Also you can refer this case study:

https://www.bestwpthemez.com/wordpress/case-study-the-specified-cgi-application-misbehaved-by-not-returning-a-complete-set-of-http-headers-%E2%80%93-wordpress-blog-2358/

Thanks,

Shane G.