IDG Answers is a community of experts who are passionate about technology. Ask a question or answer one below.
They used to call it “page faults.” It’s not really an error. Software has requested an address and the page where it resides isn’t still in main memory. Usually it has been swapped to virtual memory, (hard drive or SSD) and the OS will swap it back from virtual memory to physical memory. If you are getting massive amounts of hard faults/sec, it is usually due to too little RAM.
Here is an older article that goes into much more detail if you are interested: