Had the same problem, a came up with this solution. Can't say for sure if its the proper way to handle this, and if you ever upgrade your WP in the future, you will need to modify this file again. With that said, my solution was…
1) Locate and open the file 'wp-includes/pluggable.php'
2) On or around line '874', look for the function wp_redirect()
3) Change the current code:
//…
if ( php_sapi_name() != 'cgi-fcgi' )
status_header($status); // This causes problems on IIS and some FastCGI setups
header("Location: $location", true, $status);
//…
To this modified code:
//…
if ( php_sapi_name() != 'cgi-fcgi' )
status_header($status); // This causes problems on IIS and some FastCGI setups
try {
header("Location: $location", true, $status);
} catch (Exception $e) {
echo '';
}
//…
4) Save, Upload, and Test…
For whatever reason when the header() is set, it's throwing the error. All it wants to do is get back to the page you were editing, so by using a simple refresh, it does its job, and sends you back to the page you were on.
Good luck…