Warning on export in wp-includes/formatting.php

[kau-boy]

Trying to export the WordPress data with the export functionality you get the following warning:

Warning: strip_tags() expects parameter 1 to be string, array given in C:\xampp\htdocs\wordpress\wp-includes\formatting.php on line 2776

That happens because the export mechanism tries to use an array with the categories on the function wp_strip_all_tags() which can only get strings as a parameter.
To fix the bug you can either remove the call to wp_strip_all_tags() (wherever it takes place), or you can check the parameter of the wp_strip_all_tags() function to be a string (add to line 2772 of wp-includes/formatting.php):

// not a string
if( !is_string( $string ) )
	retrun $string;

[kau-boy]

Replying to kau-boy:
sorry, there is a typo in the 'return' statement

[kau-boy]

duplicate to #14026