内存区段错误（英语：Segmentation fault，经常被缩写为 segfault），又译为记忆段错误，也称为总线错误（bus error），或总线错误、访问权限冲突（access violation），是一种程序错误。

它会出现在当程序企图访问CPU无法寻址的内存区段时。当错误发生时，硬件会通知操作系统，产生了内存访问权限冲突的状况。操作系统通常会产生核心转储（core dump），以方便程序员进行除错。通常该错误是由调用一个地址，而该地址为空(NULL)造成的。如链表中调用一个未分配地址的空链表单元的元素。数组访问越界也可能产生这个错误。

In computing, a segmentation fault (often shortened to segfault) or access violation is a fault raised by hardware with memory protection, notifying an operating system (OS) about a memory access violation; on x86 computers this is a form of general protection fault. The OS kernel will in response usually perform some corrective action, generally passing the fault on to the offending process by sending the process a signal. Processes can in some cases install a custom signal handler, allowing them to recover on their own, but otherwise the OS default signal handler is used, generally causing abnormal termination of the process (a program crash), and sometimes a core dump.