Deprecated Constant FILTER_SANITIZE_STRING is deprecated

Here’s what GPT-4 says about this:

The PHP message Deprecated Constant FILTER_SANITIZE_STRING is deprecated means that the PHP built-in function or constant FILTER_SANITIZE_STRING is no longer recommended to use because it might be removed in future PHP versions. This is used in the PHP filter_var() function to sanitize a string.

The plugin “simple-feature-requests” seems to be using it, as indicated by the call stack in the error message.

The first step would be to check if there’s an updated version of the plugin “simple-feature-requests” that resolves this issue. Plugin authors usually work to update their plugins when deprecations like this occur.

If there’s no update or you can’t update for some reason, you could replace FILTER_SANITIZE_STRING with a suitable alternative in the plugin code yourself.

Here’s a rough example of how you might replace it with a custom function using regex to allow only alphanumeric characters (for simplicity). You’d need to modify this to suit your needs and should test it thoroughly before using it on a live site.

In the file wp-content/plugins/simple-feature-requests/templates/archive/submission-form.php (or wherever the deprecated constant is being used):


// Old: $clean_string = filter_var($dirty_string, FILTER_SANITIZE_STRING);

// New: $clean_string = preg_replace("/[^A-Za-z0-9 ]/", '', $dirty_string);


The new code snippet uses a regular expression to remove any characters that aren’t letters, numbers, or spaces. This may not be exactly equivalent to FILTER_SANITIZE_STRING, but it’s a start. It might be better to use a more comprehensive sanitization function depending on your use case.

Always remember to create a backup of your files before making changes, and test any changes on a development or staging version of your site first.