SumatraPDF Sidebar Bookmarks Missing: How to Fix the Table of Contents

If the SumatraPDF sidebar bookmarks are missing, the problem usually falls into one of four categories: the table-of-contents sidebar is hidden, the window is too narrow to show it clearly, the document contains no embedded outline, or a saved setting is preventing the expected sidebar state from returning. The correct fix depends on whether the problem affects one file or every file. The steps below focus on document-provided bookmarks and outlines, not favorites or shortcuts created by the user.

1. Confirm the Symptom With One Simple Test

Before changing settings or reinstalling anything, determine whether SumatraPDF is failing to display an available outline or whether the current document simply has no outline to display. This distinction prevents unnecessary troubleshooting.

1.1 Test With a Known Bookmarked PDF

Open a PDF that you know contains a clickable table of contents or bookmark outline. A long technical manual, standards document, or software guide often works well, but verify that its outline appears in another PDF reader first. Do not assume that visible chapter headings on the pages mean the PDF has embedded bookmarks.

After opening the test PDF in SumatraPDF, use the View menu to show the bookmarks or table-of-contents panel. Depending on the interface and build, the command may be described as bookmarks or table of contents. The F12 keyboard shortcut is also commonly used to show or hide the bookmarks panel.

Success means a navigation panel appears beside the document and contains expandable chapter or section entries. If that happens, stop changing SumatraPDF settings. The original file probably lacks an embedded outline, has a malformed outline, or uses a different kind of navigation.

If the panel remains missing or empty for a PDF whose bookmarks work in another reader, continue with the settings and layout checks below.

1.2 Identify Whether the Problem Affects One File or Every File

The scope of the symptom points toward its cause:

• If bookmarks are missing in only one document, inspect the source document and its format.
• If bookmarks are missing in every bookmarked PDF, check sidebar visibility and saved settings.
• If the panel briefly appears and then disappears after restarting, investigate settings persistence.
• If only eBooks or CHM files behave differently, compare their native table-of-contents structure with PDF outlines.

This test is more useful than reinstalling immediately because reinstalling cannot add an outline to a document that never contained one.

2. Check the Sidebar Setting and Window Layout

The bookmarks panel can be hidden independently of the document itself. It may also be present but difficult to notice because of the current window size or panel width.

2.1 Toggle the Bookmarks Panel Directly

With a known bookmarked document open, press F12 once and observe the left side of the window. If nothing changes, open the View menu and look for the bookmarks or table-of-contents command. Select it once rather than repeatedly toggling it.

If the panel appears with entries, the issue was simply sidebar visibility. Leave it open and close SumatraPDF normally so the application has an opportunity to save its state. There is no reason to edit configuration files or reinstall the program after this fix succeeds.

If an empty panel appears, that is still useful information. It indicates that the sidebar itself is working, but SumatraPDF did not find a usable outline in the current file. Repeat the test with the known bookmarked PDF before concluding that the application is malfunctioning.

2.2 Maximize or Widen the Window

Maximize the SumatraPDF window or drag its edge to make it wider. A narrow application window can make a sidebar seem absent, especially if the document area has been prioritized or the sidebar divider has been moved close to the edge.

Look along the left boundary of the document area for a narrow divider. If one is visible, drag it toward the center. Do not confuse a collapsed panel with an empty outline.

Success means the sidebar becomes visible and retains a practical width. Once the outline entries can be read and clicked, stop troubleshooting.

2.3 Verify That the Expected Application Opened the File

Windows file associations can cause a document to open in a different reader even when SumatraPDF is installed. Check the title bar, taskbar icon, or application menu to confirm that the active program is actually SumatraPDF.

If necessary, right-click the file in File Explorer, choose Open with, and select SumatraPDF for a one-time test. Changing the default association is optional and does not create bookmarks. It only ensures that the intended reader handles the file.

Success means the file opens in SumatraPDF and the expected View command or F12 behavior is available. If the file was previously opening in a browser or another reader, no deeper SumatraPDF troubleshooting is needed.

3. Check the Source Document and Its Format

SumatraPDF can display navigation supplied by supported document formats, but it cannot invent a reliable chapter hierarchy when none exists. Page headings, a printed contents page, and searchable text are not the same as embedded bookmarks.

3.1 Determine Whether the PDF Contains an Outline

Open the same PDF in another reputable reader and display that reader's bookmarks or outline panel. If the panel is also empty there, the PDF probably has no embedded outline. A scanned PDF is especially likely to contain page images without structural navigation, although searchable or digitally created PDFs can also lack bookmarks.

You can still use page navigation, search, links embedded on the pages, and any visible contents page. However, SumatraPDF cannot reconstruct author-supplied bookmarks merely from typography or chapter titles.

If you control the source document, the proper remedy is to export or generate a new PDF with bookmarks enabled. For example, the authoring application may offer an option to create PDF bookmarks from heading styles. Preserve the original file and follow the document owner's permissions and workflow.

Success means a newly exported or corrected PDF shows its hierarchy in the sidebar. At that point, the reader was functioning correctly and no settings reset is required.

3.2 Distinguish PDF Bookmarks From Page Links

A PDF can have a clickable table of contents printed on one of its pages without having a sidebar outline. Conversely, it can have sidebar bookmarks without a visible contents page. These are separate PDF features.

If links on the contents page work but the sidebar remains empty in multiple readers, the file likely contains internal links but no outline tree. That is a source-document characteristic, not evidence that SumatraPDF is not working.

3.3 Understand eBook and CHM Table of Contents Differences

EPUB and other eBook formats may provide navigation through their own table-of-contents metadata rather than a PDF-style bookmark tree. Whether entries appear, how deeply they are nested, and how they are labeled depends on the structure supplied by the eBook publisher.

CHM files also have their own compiled help navigation. Some CHM documents include a contents hierarchy, while others rely mainly on an index, links, or individual pages. A missing hierarchy in one CHM file does not prove that SumatraPDF's general sidebar feature is broken.

For comics, image collections, XPS, DjVu, and similar formats, do not assume that chapter-like filenames or visible headings automatically become bookmarks. The format and individual file must provide compatible navigation data.

Test another known-good file of the same format. If one eBook displays a table of contents and another does not, the difference is probably in the files. Stop changing global settings once that comparison confirms format-specific behavior.

3.4 Consider Permissions and Incomplete Files

A damaged, incomplete, or incorrectly downloaded document may open partially while losing access to navigation data. Download the file again from its legitimate source and save it locally before testing. Avoid editing protected files or attempting to bypass document restrictions.

If the document is on a network location, cloud placeholder, email preview, or removable drive, copy an authorized version to a normal local folder and open that copy. This rules out incomplete synchronization and transient access problems.

Codecs, Ghostscript, and printer drivers are generally not the first suspects for a missing PDF outline. They are more relevant to specific rendering, PostScript, conversion, or printing workflows. If pages display normally and only the bookmark tree is absent, focus first on the outline, sidebar state, and settings persistence.

4. Inspect or Reset SumatraPDF-settings.txt Safely

SumatraPDF stores preferences in a text settings file. A persistence problem may be involved if the sidebar can be shown during a session but its state is repeatedly lost, or if a known bookmarked PDF never produces a panel despite working in another clean SumatraPDF environment.

4.1 Close SumatraPDF Before Editing Settings

Close every SumatraPDF window before inspecting its settings. An open process may overwrite manual changes when it exits. In Task Manager, confirm that no SumatraPDF process remains if the application did not close normally.

Installed copies commonly keep user settings under the current Windows profile, in the local application data area for SumatraPDF. Portable copies may keep their settings alongside the executable when that location is writable. The exact active location depends on how the program is launched and configured.

Do not delete the file immediately. First copy SumatraPDF-settings.txt to a safe backup location. This preserves preferences such as display choices, history behavior, and other customizations.

4.2 Check Whether the Settings File Can Be Written

Show the sidebar, close SumatraPDF normally, reopen it, and test the same bookmarked PDF. If the chosen state never persists, inspect the settings file's modified time. If it does not update, the file or its folder may be read-only, protected, or unavailable to the current Windows account.

This can occur with a portable copy placed in a restricted folder such as Program Files, on read-only media, or in a location controlled by organizational policy. Move an authorized portable copy to a user-writable folder for testing, or use the installed edition under the appropriate account.

Success means the settings file updates after a normal exit and the desired sidebar state returns on the next launch. Stop there rather than changing unrelated Windows permissions.

4.3 Reset by Renaming, Not Permanently Deleting

For a reversible reset, close SumatraPDF and rename the active SumatraPDF-settings.txt file to something such as SumatraPDF-settings-backup.txt. Launch SumatraPDF again so it can create fresh defaults, then open the known bookmarked PDF and show the sidebar.

If bookmarks now appear, an old setting or damaged preference state was likely involved. Reapply only the preferences you need. Avoid copying the entire old settings file back, because that can restore the original problem.

If the reset makes no difference, close the program and restore the backup if desired. A failed reset is a signal to return attention to the source file, active executable, or portable-versus-installed setup rather than repeatedly deleting preferences.

5. Run a Clean Temporary Test Before Reinstalling

A clean test separates application behavior from existing settings without destroying the current setup. It is especially useful when installed and portable copies may coexist.

5.1 Use a Separate Authorized Portable Copy

Obtain SumatraPDF only from its official website. Place a portable copy in a new, user-writable folder, launch it directly from that folder, and open the same known bookmarked PDF. Do not copy your existing settings into the test folder.

Confirm the executable path through Task Manager or the file's shortcut properties if there is any doubt about which copy is running. Windows shortcuts and file associations can continue launching an older installed copy even after a newer portable copy has been downloaded.

Success means the clean copy shows the outline. This points to the original copy's settings, launch path, or write permissions. Keep the clean result as a reference and repair the original configuration only if you need to preserve it.

5.2 Know When Reinstallation Is Appropriate

Reinstallation is reasonable only after a known bookmarked PDF fails in a clean test and you have confirmed that the intended executable is running. Even then, reinstalling is unlikely to fix a document that lacks an outline.

Before reinstalling, record whether the panel itself was missing, whether it appeared empty, and whether the test document worked in another reader. Those observations are more diagnostic than the general statement that SumatraPDF is not working.

If a fresh official copy displays the bookmarks correctly, stop. If it does not, compare the exact test document and its outline in another reader. A reproducible discrepancy with a valid file may warrant checking the official SumatraPDF documentation or reporting the issue with a non-confidential sample document.

6. Quick Fix Checklist

1. Open a PDF whose embedded bookmarks are known to work in another reader.
2. Press F12 or use the View menu to show the bookmarks or table-of-contents panel.
3. Maximize the window and widen any narrow divider at the left edge.
4. Confirm that Windows opened the file in SumatraPDF rather than a browser or different reader.
5. Test whether the issue affects one document, one format, or every bookmarked PDF.
6. Remember that a visible contents page does not guarantee an embedded PDF outline.
7. For EPUB or CHM files, test another known-good file of the same format.
8. Close SumatraPDF and verify that its settings file is writable and updating.
9. Back up and rename SumatraPDF-settings.txt for a reversible settings reset.
10. Run a clean portable copy from a separate writable folder before reinstalling.

You have found the fix when the known bookmarked test document shows a populated navigation tree and its entries jump to the expected sections. Once that happens, stop changing settings. If only the original document remains empty, the source file is the likely cause.

7. Frequently Asked Questions

7.1 Why is the SumatraPDF bookmarks sidebar completely missing?

It is often hidden by the current sidebar setting or obscured by a narrow window. Press F12 or use the relevant command in the View menu, then maximize the window and inspect the left edge for a collapsed divider. Test with a known bookmarked PDF so you are not troubleshooting against an empty source file.

7.2 Why is the sidebar visible but empty?

An empty panel usually means the current document provides no usable outline. Check the same file in another reader. If its bookmark panel is empty there as well, SumatraPDF has nothing to display. Printed chapter headings and clickable page links do not automatically create a sidebar outline.

7.3 Can SumatraPDF generate bookmarks from headings?

SumatraPDF is primarily a document reader, not a PDF authoring system. It displays navigation supplied by the file but cannot reliably invent an author-approved outline from visual headings. If you own the source, export the PDF again with bookmark creation enabled in the authoring software.

7.4 Why does one EPUB or CHM file have a table of contents while another does not?

The files may contain different navigation structures. An EPUB publisher can include a detailed hierarchy, a minimal list, or faulty metadata. A CHM file may rely on contents, index, search, or page links in different combinations. Compare files of the same format before resetting global settings.

7.5 Why does the sidebar setting disappear after restarting?

The active SumatraPDF-settings.txt file may not be saving. This can happen when a portable copy runs from a read-only or protected folder, when multiple copies use different settings locations, or when the application does not close normally. Verify the file's modified time, folder permissions, and the path of the executable you are actually launching.

7.6 Do I need Ghostscript, a codec, or a printer driver to restore PDF bookmarks?

Usually not. If PDF pages render correctly and only the outline is missing, those components are unlikely to be the cause. Ghostscript or external tools may matter in particular PostScript, conversion, or printing workflows, but an ordinary PDF bookmark tree comes from the PDF's own structure. Start with the source outline and sidebar state instead.