If you’re reading this, you might have been told by SumatraPDF that you have a corrupted installation.

SumatraPDF comes in two flavors: a portable version and an installer.

A portable version is a self-contained executable and cannot be corrupted.

An installer needs to be run to be properly installed. Part of it is extracting libmupdf.dll library.

There are 2 possible problems:

If you want to place SumatraPDF in any location, under any name, use the self-contained portable flavor.

If you insist on using the installable version, just install it. The installer will run if it has -install in the name of the .exe (which it will if you download official build).

If you rename the .exe, you can force running the installer with -install option.

Alternatively, you can extract libmupdf.dll and all other files with -x option.