# Failed to load libmupdf.dll

When installed, SumatraPDF consists of 2 files:
* `SumatraPDF.exe`
* `libmupdf.dll`

You're reading this page because loading of `libmupdf.dll` failed and we can't proceed.

**How can that happen?**

There are many possible reasons.

Error code and error message is what Windows OS says the problem is.

To learn more about that specific error:
* you can Google: `LoadLibrary <error-code>`
* you can ask any AI: `when calling LoadLibrary() win32 api I got an error <error code>. Tell me what it means`

Or you can ask in [SumatraPDF forums](https://github.com/sumatrapdfreader/sumatrapdf/discussions).