# Installation SumatraPDF is distributed in several forms. Pick the one that matches how you want to deploy it. ## Download flavors | Flavor | What you get | Best for | | --- | --- | --- | | **Installer** (`SumatraPDF--install.exe`) | Installs to `%LOCALAPPDATA%\SumatraPDF` (or `%PROGRAMFILES%` with `-all-users`), registers file associations, optional preview handler | Most users | | **Portable** (`SumatraPDF-.exe` downloaded as `SumatraPDF-.zip`) | Single self-contained `.exe` — no separate `libsumatrapdf.dll`, settings live next to the exe | USB stick, custom folder, no installer | | **Extract only** (`-x`) | Unpack files without installing | IT scripts, inspection | Download from [sumatrapdfreader.org](https://www.sumatrapdfreader.org/download-free-pdf-viewer) or [pre-release](https://www.sumatrapdfreader.org/prerelease). ## Running the installer Double-click the installer, or silently: ``` SumatraPDF--install.exe -install -silent ``` Common options — full list in [Installer cmd-line arguments](Installer-cmd-line-arguments.md): | Option | Meaning | | --- | --- | | `-d ` | Install directory | | `-all-users` | Install to `%PROGRAMFILES%\SumatraPDF` for all users (**ver 3.4+**) | | `-with-preview` | Register PDF preview in File Explorer | | `-with-filter` | Register Windows Search PDF filter | | `-log` | Write log to `%LOCALAPPDATA%\sumatra-install-log.txt` | ## Extract without installing ``` SumatraPDF-64-install.exe -x -d "C:\Temp\Sumatra" ``` Extracts `SumatraPDF.exe`, `libsumatrapdf.dll`, `sumatrapdf-tool.exe`, etc. into the target directory. Does **not** register file associations. Recent builds do not create Start Menu / desktop shortcuts when extracting only. ## Portable vs installed settings | | Portable | Installed | | --- | --- | --- | | Settings file | Same folder as `.exe` | `%LOCALAPPDATA%\SumatraPDF\SumatraPDF-settings.txt` | | Thumbnail cache | `sumatrapdfcache` next to exe | `%LOCALAPPDATA%\SumatraPDF\sumatrapdfcache` | Override with `-appdata ` — see [Command-line arguments](Command-line-arguments.md) and [How we store settings](How-we-store-settings.md). ### Custom settings directory (enterprise / RDP) Launch shortcuts with: ``` SumatraPDF.exe -appdata "D:\Shared\SumatraSettings" ``` All users sharing that path use the same `SumatraPDF-settings.txt`. Ensure the directory is writable by every account that runs SumatraPDF. ## Upgrade fails: file in use (PdfFilter.dll / PdfPreview.dll / libsumatrapdf.dll) Through **3.6** the engine DLL was named `libmupdf.dll`; from **3.7** it is `libsumatrapdf.dll`. When upgrading, the installer renames existing DLLs aside before writing new ones. That can fail if Windows still has the old file open: | File | Often locked by | | --- | --- | | **PdfFilter.dll** | **Windows Search** (`SearchIndexer.exe`, `SearchFilterHost.exe`) after PDF IFilter registration | | **PdfPreview.dll** | **File Explorer** preview pane / `dllhost.exe` / `prevhost.exe` | | **libsumatrapdf.dll** | Running **SumatraPDF**, Explorer preview, or Search filter hosts | Typical Windows errors during install: **32** (sharing violation / file in use), **5** (access denied on replace/delete). ### What the installer does 1. Unregisters the search filter and preview handler (if installed) 2. Stops the **Windows Search** service (`WSearch`) when possible 3. Kills processes that still load install-dir modules 4. Renames `PdfFilter.dll`, `PdfPreview.dll`, and `libsumatrapdf.dll` to `*.copy` 5. If a rename stays blocked, shows a dialog and **retries every few seconds** until success or you abort ### What you can do 1. **Close** all SumatraPDF windows and other PDF apps 2. **Close** Explorer windows that show a **PDF preview** pane (or turn off the preview pane) 3. Temporarily **stop Windows Search**: - `Win+R` → `services.msc` → **Windows Search** → Stop - Or elevated: `net stop WSearch` 4. Run the installer again (as admin for “all users” under Program Files) 5. After install, start Windows Search again if you stopped it (`net start WSearch`) If the install still fails, reboot and run the installer **before** opening PDFs or browsing folders with preview enabled. ## Corrupted or incomplete installation If SumatraPDF reports a [corrupted installation](Corrupted-installation.md): - `libsumatrapdf.dll` is missing next to `SumatraPDF.exe`, or - `libsumatrapdf.dll` version does not match `SumatraPDF.exe` **Fix:** run the official installer, use the portable exe, or extract with `-x` so both files match. Also see [Failed to load libsumatrapdf.dll](Failed-to-load-libmupdf.md) if the app starts but cannot load the DLL (often antivirus). ## Installer runs when I open a PDF SumatraPDF only shows the installer UI when the executable name contains `-install` (official installers rename themselves that way) or you pass `-install`. If double-clicking a PDF launches an installer: - File association may point at the **installer .exe** instead of installed `SumatraPDF.exe` - You may be running a copied installer from Downloads instead of the installed copy Re-run the [official installer](https://www.sumatrapdfreader.org/download-free-pdf-viewer), then check [Set as default PDF viewer](Set-as-default-pdf-viewer.md). ## Multiple copies / old versions An older SumatraPDF in `%LOCALAPPDATA%` or a renamed portable copy can confuse file associations. [Uninstall](Uninstalling-SumatraPDF.md) via Settings → Apps, then install fresh. ## Admin vs normal user Do **not** run SumatraPDF as administrator for everyday reading. An elevated instance cannot open files dropped from a normal Explorer session ("running as admin and cannot open files from a non-admin process"). ## Set as default viewer After installing, follow [Set as default PDF viewer](Set-as-default-pdf-viewer.md). The portable exe alone does not register defaults. ## Command-line tools After a full install, `sumatrapdf-tool.exe` is next to `SumatraPDF.exe` and on PATH. With the portable EXE you can run the same commands as `SumatraPDF.exe ` (see [Tools](Tools.md)), or extract `sumatrapdf-tool.exe` with `-x`. No install required. ## See also - [Portable vs installer](SumatraPDF-portable.md) — pre-3.7 vs 3.7 single-EXE layout, where the DLL is extracted, installer name / `-install` flag - [FAQ](FAQ.md) - [Corrupted installation](Corrupted-installation.md) - [Uninstalling SumatraPDF](Uninstalling-SumatraPDF.md) - [Installer cmd-line arguments](Installer-cmd-line-arguments.md)