MailClient.exe - System Error - libmupdf.dll is missing

Hi there! I’ve been recently receiving the following error message upon opening eM Client:

MailClient.exe - System Error

The program can’t start because libmupdf.dll is missing from your computer. Try reinstalling the program to fix this problem.


After I click OK, the program runs normally, but from times to times it shows me this error and I dont understand what could be the problem, could you help me, please?

Thank you and regards!

miércoles 14 octubre 2020 :: 1144hrs (UTC +01:00)

Hi @oscar

You don’t say which version you are running, however, first step is to run the latest MSI installation setup this will either update or give you 2 options - chose REPAIR then take it from there.

The latest release version of EM Client V8.0.3385.0 Windows or V8.0.3494.0 Mac

eMClient Release History is here:

¡Saludos desde la soleada España!


[email protected]

Hi, I’m using the latest version for Windows, and I’ve already reinstalled it, but the error keeps showing from time to time…

jueves 15 octubre 2020 :: 1839hrs (UTC +01:00)

Hi @oscar

I just scanned my system, I do not have ‘libmupdf.dll’ on my system.
An internet search indicates that ‘libmupdf.dll’ is part of a program named SumatraPDF which presumably is or has been installed on your system.
To resolve the issue you will probably need to reinstall or repair SumatraPDF

It is not an eMC fault.

¡Saludos desde la soleada España!


[email protected]

Hi, you were right, it had something to do with Sumatra PDF Reader. I talked to them and they helped me out, all good now!

I also have the problem of EMClient indicating that the file libmupdf.dll is missing. As the first post here indicated the message that EMclient can’t start because of that file missing appears regularly on my laptop, even when EMClient is in fact up and running. I do NOT have SumatraPDF installed, and never had. So to me this is clearly an EMClient error. And related to version 8; it never happened with version 7. Reinstalling doesn’t help.

I am running version 8 on Windows 7.

The eM Client install file has all the dependencies eM Client needs.

Uninstall eM Client, making sure NOT to delete the database directory when asked. That will enable all your data and settings to be there later.

Download and install the latest version from the Release History.

domingo 25 octubre 2020 :: 1327hrs (UTC +01:00)

Hi @JossSwen

First the error issue with ‘libmupdf.dll’ is not a fault with eMC

Have you investigated the issue of ‘libmupdf.dll’ on the internet?

As I am curious, I have just done another search through GIT and discovered that the file was developed by Artifex Software for Ghostscript
Ghostscript is a suite of software based on an interpreter for Adobe Systems’ PostScript and Portable Document Format (PDF) page description languages. Its main purposes are the rasterization or rendering of such page description language files, for the display or printing of document pages, and the conversion between PostScript and PDF files.
Ghostscript can be used as a raster image processor (RIP) for raster computer printers, for instance, as an input filter of line printer daemon, or as the RIP engine behind PostScript and PDF viewers. It can also be used as a file format converter, such as PostScript to PDF converter. The ps2pdf conversion program comes with the ghostscript distribution.

Ghostscript can also serve as the back-end for PDF to raster image (png, tiff, jpeg, etc.) converter; this is often combined with a PostScript printer driver in “virtual printer” PDF creators. As it takes the form of a language interpreter, Ghostscript can also be used as a general purpose programming environment.

So the resultant is that ‘libmupdf.dll’ is NOT exclusive to SumatraPDF it is used by a host of printers and other stuff. So I guess SumatraPDF was a lucky first hit.

Only you will know what software you have installed and products you use, so I suggest you investigate this further.

¡Saludos desde la soleada España!


[email protected]

This issue is not because of Sumatra. I use it, and have never had the problem.

Just uninstall eM Client, then install it again from a new download. All the dependencies will be there.

domingo 25 octubre 2020 :: 1634hrs (UTC +01:00)

Hi @Gary

I also use Sumatra and have never had a problem, my comment, this was because of comments by…

Hi, you were right, it had something to do with Sumatra PDF Reader. I talked to them and they helped me out, all good now!

It is, however, strange that some people have problems where others do not, or is it?

¡Saludos desde la soleada España!


[email protected]

1 Like

Hi, thanks for responding. But it doesn’t explain the error message, which clearly says at the tope: Mailclient.exe - System Error. I guess maybe version 8 is trying to use some of that ghostscript?


What happened when you uninstalled, then downloaded and reinstalled?

Tried that. No change unfortunately. And the recent updated version also didn’t make things any better. Anyway, the main problem remains the way version 8 does the windows management, as per my earlier post: 1) No longer closing all open windows when closing the main EMClient window (a change that I really don’t understand), and 2) freezing when you are in a message composition window and want to go to the desktop via the “Show desktop” button. Also not showing the desktop then. This happens without fail.