How to use pre_upload_error filter in WordPress

pre_upload_error filter

Returning a truthy value will effectively short-circuit the media upload, returning that value as a 500 error instead.

To use the pre_upload_error filter, first you have to register it using add_filter. You can write this code into the functions.php of your activated theme or in a custom WordPress Plugin.

We at WePlugins always prefer to create a custom WordPress Plugin while using hooks so nothing breaks when you update your WordPress Theme in the future.

In the below live example, we have defined a function weplugins_modify_pre_upload_error_defaults which takes 1 parameter and we registered it using add_filter. The first parameter pre_upload_error is the name of the hook, the second parameter weplugins_modify_pre_upload_error_defaults is the name of the function which needs to be called, the third parameter is the priority of calling the hook if the same hook is used multiple times, and the last parameter is the number of arguments (if any) to be passed in the registered function.

Sometimes, you have to remove a registered hook so you can use remove_filter to remove the pre_upload_error filter.

Parameters

Below the 1 parameter is required to use this hook.

• $error : (bool) Whether to pre-empt the media upload. Default false.

Live Examples

Example 1: Basic Usage

Below is an example of how you can use this hook.

    function weplugins_modify_pre_upload_error_defaults($error) { 
        // Update the $error variable according to your website requirements and return this variable. 
        // You can modify the $error variable conditionally too if you want.
        return $error; 
    }
    // add the filter
    add_filter("pre_upload_error", "weplugins_modify_pre_upload_error_defaults", 10, 1);
    

Example 2: Conditional Error Handling

In this example, the error is conditionally modified based on a specific condition.

    function weplugins_modify_pre_upload_error_conditionally($error) { 
        if (some_condition()) {
            $error = true; // Trigger the error conditionally
        }
        return $error; 
    }
    // add the filter
    add_filter("pre_upload_error", "weplugins_modify_pre_upload_error_conditionally", 10, 1);
    

Example 3: Removing the Hook

To remove a hook callback, use the example below.

    remove_filter("pre_upload_error", "weplugins_modify_pre_upload_error_defaults", 10, 1);
    

Please make sure to provide the same callback function name, priority, and number of arguments while removing the hook callback.