PFN_vkDebugUtilsMessengerCallbackEXT(3)

# PFN_vkDebugUtilsMessengerCallbackEXT(3) Manual Page

## Name

PFN_vkDebugUtilsMessengerCallbackEXT - Application-defined debug messenger callback function

## C Specification

The prototype for the VkDebugUtilsMessengerCreateInfoEXT::`pfnUserCallback` function implemented by the application is:

    // Provided by VK_EXT_debug_utils
    typedef VkBool32 (*PFN_vkDebugUtilsMessengerCallbackEXT)(
        VkDebugUtilsMessageSeverityFlagBitsEXT      messageSeverity,
        VkDebugUtilsMessageTypeFlagsEXT             messageTypes,
        const VkDebugUtilsMessengerCallbackDataEXT* pCallbackData,
        void*                                       pUserData);

## Parameters

- `messageSeverity` specifies the VkDebugUtilsMessageSeverityFlagBitsEXT that triggered this callback.

- `messageTypes` is a bitmask of VkDebugUtilsMessageTypeFlagBitsEXT specifying which type of event(s) triggered this callback.

- `pCallbackData` contains all the callback related data in the VkDebugUtilsMessengerCallbackDataEXT structure.

- `pUserData` is the application-defined user data pointer, equal to the value of VkDebugUtilsMessengerCreateInfoEXT::`pUserData` specified when the VkDebugUtilsMessengerEXT object was created.

## Description

The callback returns a VkBool32, which is interpreted in a layer-specified manner. The application should always return VK_FALSE. The VK_TRUE value is reserved for use in layer development.

Valid Usage

- VUID-PFN_vkDebugUtilsMessengerCallbackEXT-None-04769
  The callback must not make calls to any Vulkan commands

## See Also

VK_EXT_debug_utils, VkBool32, VkDebugUtilsMessageSeverityFlagBitsEXT, VkDebugUtilsMessageTypeFlagsEXT, VkDebugUtilsMessengerCallbackDataEXT, VkDebugUtilsMessengerCreateInfoEXT

## Document Notes

For more information, see the Vulkan Specification.

This page is extracted from the Vulkan Specification. Fixes and changes should be made to the Specification, not directly.

## Copyright

Copyright 2014-2026 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0