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Hi! I’ve been using Sumatra PDF reader for a while now and I’ve been recently having a problem with my email client (eM Client) regarding pdfs. I get the following error message:
“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.”
I talked to eM Client support and they said it’s not their problem, as they don’t use the libmupdf.dll file, so it must be something related to Sumatra.
I’ve checked the presence of the file in my system and it’s there, under Sumatra PDF reader program folder, I’ve even reinstalled Sumatra and my email client, but the problem persists, whenever I work with pdf files in emails.
I’m using Windows 7 32-bit.
Do you know what could be the problem?
Thank you and best regards!


Unfortunately if you reinstalled and its not functioning then the reinstallation is not applying its self the same way it was the first time round.

Why ? would e-mail call SumatraPDF, is SumatraPDF somehow set as previewer for calling pdf in e-mail ?

Since it was last working well (how were the two configured) , did you try to update/use a different version of sumatrapdf or email client.

When you installed first time, was it version 3.1.2 32bit, and was it optionally enabled for previewing pdf ? if you have up-reved since then, the installation folders may have changed.

I would suggest the following sequence.
Uninstall whatever version you are currently running, that should remove the libmupdf.dll along with the other files.
Check there are no remnants after uninstallation. so from a cmd prompt run
where /r c:\ libmupdf.dll
It may take some time to check that whole drive, and naughty me I currently have thirteen active and counting ! but there should only be one each for 32bit and 64bit SumatraPDF and perhaps a couple for some other apps.
decide why there may be a reason for any that remain.
Once happy there are none unaccounted for, reboot, then install sumatra 3.1.2 32bit installer.
You can copy and paste the first entry on this page

I suggest you DO NOT install the previewer the first time, to check if that is what causes the error message.
Check all is working well by saving pdf attachments from e-mail and view them as if a standard user.
No error message should appear at that point since both should be standalone applications.
Now if you were using the previewer ( like an Outlook user), uninstall again and reinstall a second time with the preview option activated.
Again no error message should appear at that point.


Hi, thank you for your support, it worked! I’ve updated to 3.2 and all is good now.