Quick answers to common questions from the GitHub discussions forum. Each item links to a page with more detail.
Opening files and windows #
I enabled tabs but every PDF opens in a new window
Check
ReuseInstance = true in advanced settings. With ReuseInstance = false, Windows starts a separate SumatraPDF process for each file, so tabs cannot be shared. See Tabs and windows.How do I open a file in a new window instead of a tab?
SumatraPDF asks to install when I double-click a PDF
This usually means the
.exe you are running has -install in its name (the installer renames itself that way) or libmupdf.dll is missing next to the executable. Download the official build and run the installer, or use the portable (self-contained) version. See Installation and Corrupted installation.SumatraPDF is running as admin and cannot open files from a non-admin process
Do not run SumatraPDF elevated. Run it as a normal user, or run the program that opens the file with the same privilege level.
Settings and display #
I changed the default layout but reopening a file ignores it
DefaultDisplayMode and DefaultZoom apply when you open a file for the first time. After that, per-document state restores the layout from when you last closed the file. To reset a file, remove its entry from FileStates in advanced settings or delete the settings file.View settings from the menu don’t take effect
Some settings (for example
UseTabs) require restarting SumatraPDF. Per-document settings override global defaults for files you have opened before. See How we store settings.I accidentally inverted document colors — how do I undo?
Press
Shift + I again (CmdInvertColors), or set FixedPageUI.InvertColors = false in advanced settings. See Customize theme colors.How do I get a dark background without inverting images in EPUBs?
There is no perfect one-click solution:
Shift + I inverts the whole rendered page including images. For EPUBs you can tune EBookUI (custom CSS, WindowBgCol) or use themes — see Customizing eBook UI.Links and navigation #
SumatraPDF turns plain-text URLs into clickable links
SumatraPDF auto-detects URLs and email addresses in PDF text (a long-standing PDF viewer convention). Embedded hyperlinks in the file are separate. Set
DisableAutoLinks = true in advanced settings to turn off auto-detection only. See Hyperlinks.I followed an internal link (footnote) — how do I go back?
Search #
Search shortcuts don’t work / F3 changes volume on my laptop
F3 only works when keyboard focus is in the document, not in the find box. On many laptops you need Fn + F3. See Finding text.Printing #
Command-line printing uses the wrong paper size or tray
Use explicit
-print-settings tokens (paper=, bin=, paperkind=). On Windows 11 the print dialog may hide Advanced options — CLI printing avoids that. See Printing.Annotations #
How do I change default highlight color or size?
Edit the
Annotations section in advanced settings (HighlightColor, FreeTextSize, etc.). There is no global undo for annotations. See Editing annotations.PDF tools (merge, split, delete pages) #
How do I delete the last page without knowing the page count?
Use
sumatrapdf-tool clean with N as the last-page marker, e.g. 1-N-1 keeps all pages except the last. See Tools and Delete pages from PDF.Accessibility #
Can SumatraPDF read a document aloud?
Yes — pre-release 3.7+ adds Read Aloud via the command palette (
Ctrl + K, type read aloud) using Windows text-to-speech. See Accessibility and Text-to-Speech.Default PDF viewer #
SumatraPDF doesn’t appear in Windows Default apps
Install from the official installer (not only the portable exe), then set defaults manually. See Set as default PDF viewer and Installation.
Still stuck? #
- Search discussions — your question may already be answered
- Report a bug if something is broken
- Request a feature on the feature board