What is a .dmp file?

About the format

A .dmp file is a snapshot of memory that Windows writes when something crashes. There are two very different kinds hiding behind the same extension. Kernel dumps are written when the whole system blue-screens: the small ones land in C:\Windows\Minidump (usually 256 KB to a few MB), and the big MEMORY.DMP in C:\Windows can run to gigabytes. They start with the bytes PAGEDU64 (or PAGEDUMP on 32-bit systems) and contain the stop code, its four parameters, the list of loaded drivers and the crash stack — everything needed to work out which driver took the machine down. Application minidumps, by contrast, start with the bytes MDMP and describe a single program crashing; Task Manager's right-click → Create dump file makes these, and so does Windows Error Reporting. Tools that expect one kind will refuse the other, which is the single most common source of confusion with .dmp files — if a 'minidump reader' rejects your file, you probably have the other flavour.

How to open a .dmp file

Is a .dmp file dangerous?

Not executable — a dump can't run. It can, however, contain fragments of whatever was in memory (window titles, occasionally credentials), so treat big MEMORY.DMP files as private data and think before sharing one publicly.

Related file types