SumatraPDF Restore Session Not Working: How to Fix It

When SumatraPDF does not reopen the tabs or windows from your previous session, the cause is usually a disabled restore preference, settings that were not saved during shutdown, a special launch mode, an unreadable settings file, or invalid data inside the saved session. This is different from SumatraPDF forgetting the last page viewed in one document. Session restoration concerns the complete set of open tabs and, where supported, their window layout. Work through the checks below in order, stopping as soon as a small controlled test succeeds.

1. Confirm the Symptom With a Simple Session Test

Before editing settings, confirm that session restoration itself is failing. A document that was moved, deleted, disconnected, or blocked can make a saved session look broken even when SumatraPDF attempted to restore it.

1. Open SumatraPDF normally from the Start menu or your usual desktop shortcut.
2. Open two small local PDF files from a folder such as Documents.
3. Leave both files open in separate tabs.
4. Close SumatraPDF using the window's Close button or the application's Exit command.
5. Wait a few seconds, then launch SumatraPDF from the same shortcut.

Success means both test documents return as tabs. If they do, session restore is working. The original problem is probably limited to particular files, storage locations, launch commands, or formats. Stop changing global settings and investigate the affected documents instead.

If SumatraPDF opens with no restored tabs, continue with the settings checks. If the tabs return but pages are blank, display incorrectly, or trigger errors, that is a rendering or format-support issue rather than a failure to restore the session.

1.1 Distinguish Session Restore From Remembering a Page

Opening one document and returning to its previous page does not prove that the previous application session was restored. SumatraPDF can retain information about previously opened files without automatically reopening all of them at startup.

Use two documents for the test. That makes it easy to tell whether the tab set was recreated. Also note whether multiple windows return if you normally use more than one window. A restored file list without the expected tab or window arrangement can indicate damaged or incomplete session data.

2. Check the Settings and Launch Method Directly Related to Session Restore

The two most relevant advanced settings are RestoreSession and RememberOpenedFiles. Their precise presentation can vary by release, but their roles are distinct.

• RestoreSession controls whether SumatraPDF attempts to reopen the previous session at startup.
• RememberOpenedFiles allows SumatraPDF to retain information about opened documents. Disabling it can prevent useful history and session information from being retained.
• SessionData stores the actual saved session state, including information used to reconstruct tabs and window layout.

Open SumatraPDF's advanced settings from its Settings menu. Confirm that RestoreSession is set to true. If you want opened documents remembered, also confirm that RememberOpenedFiles is true. Save the file without changing unrelated values.

Close SumatraPDF cleanly, reopen it, create the two-document test session, close it cleanly again, and relaunch. Success means both tabs return. Once that happens, stop editing the settings file.

2.1 Inspect the Shortcut and Command Line

How SumatraPDF starts can affect restoration. Right-click the shortcut you use, open Properties, and inspect the Target field. A normal shortcut generally points to the SumatraPDF executable without testing arguments or an unexpected alternate settings directory.

Testing-oriented launches are designed to create controlled behavior and may skip normal session restoration. If a shortcut, script, launcher, or debugging setup invokes SumatraPDF in a for-testing mode, including a testing command-line option such as -test-app, remove that option for everyday use. Do not alter a managed workplace shortcut without checking with your administrator.

Also compare different launch methods. Starting the application by itself is the clearest test. Double-clicking a PDF asks Windows to launch SumatraPDF with that file as an argument. Depending on the instance and tab behavior, the requested file can influence what appears at startup and make the result look different from an ordinary session restore.

2.2 Verify the Windows File Association

A file association does not normally control RestoreSession, but a stale association can launch a different copy of SumatraPDF. This commonly happens when an installed copy and a portable copy both exist.

In Windows Settings, check the default application for PDF or another affected format. Then compare the executable path with the copy you launch manually. If double-clicking a document opens one copy while the Start menu opens another, each copy may be reading a different settings file and maintaining separate session data.

Success means every intended launch method opens the same SumatraPDF installation and uses the same preferences. If session restoration now behaves consistently, no reset is necessary.

3. Check Windows, Document, and Format Factors

A restored session can contain valid entries that SumatraPDF can no longer open. Test local, ordinary PDF files first so that unavailable resources do not obscure the diagnosis.

3.1 Confirm That Saved Documents Still Exist

Check whether the documents from the previous session were renamed, moved, or deleted. Files on network shares, removable drives, cloud-synchronized folders, and temporary download locations may not be available when SumatraPDF starts.

For a reliable test, copy two unrestricted documents to a local folder that your Windows account can read. Open them, exit cleanly, and restart SumatraPDF. If these local files return, the restore mechanism is functioning and the original source location is the problem.

3.2 Check File and Folder Permissions

SumatraPDF needs permission to read the restored documents and permission to update its settings file. Windows security controls, folder permissions, antivirus protection, enterprise policies, or read-only media can interfere with one or both operations.

Do not bypass document restrictions or security controls. Instead, verify that the file opens normally from File Explorer under your regular Windows account. Then verify that the relevant settings folder is writable. Running SumatraPDF as administrator is not a good permanent fix because it can create a different security context and hide the real permissions problem.

3.3 Separate Format Problems From Session Problems

SumatraPDF supports several document and image categories, but a restored item can still fail because it is corrupt, incomplete, unsupported in its particular form, or dependent on unavailable components. If the tab appears but its contents do not render, SumatraPDF successfully restored at least that session entry.

External components such as Ghostscript are relevant to certain PostScript workflows, not to the basic act of restoring ordinary PDF tabs. Likewise, image codecs, printer drivers, and print services do not normally determine whether a previous session reopens. Investigate those components only when the corresponding format fails to render or printing fails after the tab has already returned.

If only one eBook, comic archive, CHM, DjVu, XPS, image, or other document fails, open that file manually. If manual opening also fails, troubleshoot the file or format. Do not delete otherwise healthy session settings to solve a document-specific error.

4. Inspect or Reset SumatraPDF-settings.txt Safely

SumatraPDF stores user preferences and session information in SumatraPDF-settings.txt. The file's location depends on whether you use the installed or portable application.

• An installed copy normally keeps its settings under the current Windows user's local application data area, commonly in the SumatraPDF folder under %LOCALAPPDATA%.
• A portable copy normally keeps its settings beside the SumatraPDF executable, provided that folder is writable.
• A custom launch command can direct the application to a different data location.

The safest way to locate the active file is to use the advanced settings command from inside the exact SumatraPDF copy that is misbehaving. This avoids editing a similarly named file belonging to another installation.

4.1 Confirm That Settings Persist

Make a harmless, easily reversible preference change through SumatraPDF, close the application normally, and reopen it. If the change does not persist, the settings file may be read-only, its folder may not be writable, or SumatraPDF may be loading another settings file.

Session information is written during normal application operation and shutdown. If Windows terminates the process, the computer loses power, a cleanup utility removes the file, or SumatraPDF crashes, the most recent session may not be saved. Always perform a clean exit during testing.

Success means the harmless preference remains changed after restart and a fresh two-tab session is restored. Revert the test preference if desired, then stop troubleshooting.

4.2 Back Up the File Before Editing SessionData

Close every SumatraPDF window before manually editing the settings file. Then copy SumatraPDF-settings.txt to a safe backup location. Editing while SumatraPDF is running is unreliable because the application may overwrite your changes when it exits.

Open the settings file in a plain-text editor. Confirm that RestoreSession and RememberOpenedFiles have the intended values. Look for SessionData. If session restoration is enabled but the saved session is malformed, stale, or inconsistent, resetting only the session data may be enough.

4.3 Reset Bad Session Data Carefully

The lowest-risk approach is to preserve a backup and remove or clear only the SessionData block, rather than deleting the entire settings file. Be careful to remove the complete block with balanced braces and not unrelated preferences. If you are unsure where the block begins and ends, use the clean temporary test described in the next section instead of hand-editing it.

After resetting SessionData, start SumatraPDF. It should open without the old tabs because the damaged session has been intentionally removed. Open two local PDFs, close SumatraPDF normally, and launch it again.

Success means the newly created tabs return. The old session cannot be recovered from the reset file, but it may remain available in your backup for reference. Do not copy the suspect SessionData back into a working configuration.

5. Run a Clean Temporary Test Before Reinstalling

A clean test determines whether the problem belongs to your normal configuration or to the application and launch environment. It is more informative than immediately reinstalling, because reinstalling may leave per-user settings untouched.

1. Close all SumatraPDF windows and verify in Task Manager that no SumatraPDF process remains.
2. Back up the active SumatraPDF-settings.txt file.
3. Rename the original settings file, for example to SumatraPDF-settings.backup.txt.
4. Start SumatraPDF normally so it can create a fresh configuration.
5. Enable session restoration if it is not enabled in the fresh configuration.
6. Open two small local PDF files.
7. Exit cleanly, wait briefly, and reopen SumatraPDF through the same shortcut.

If the two tabs return, the executable is working and the original settings file contains the problem. Restore preferences selectively rather than replacing the new file wholesale with the old one. In particular, avoid restoring the old SessionData.

If the clean configuration also fails, check the shortcut again, confirm that no for-testing mode is active, verify that the settings file is actually being created and updated, and make sure another SumatraPDF process is not holding the session. Only then consider downloading a current installer or portable package from the official site.

Reinstallation is useful when application files are missing or damaged, but it will not necessarily repair an unwritable profile folder, a testing command line, or corrupted settings retained in the user's application data.

6. Quick Fix Checklist

• Test with two small local PDFs, not network, removable, cloud-only, or temporary files.
• Set RestoreSession to true.
• Keep RememberOpenedFiles enabled when you want document history and sessions retained.
• Close SumatraPDF normally so the latest SessionData can be saved.
• Launch from the same shortcut during every test.
• Remove testing-oriented command-line options from normal shortcuts.
• Confirm Windows is not launching a different installed or portable copy.
• Edit the settings file opened by the affected SumatraPDF instance.
• Back up SumatraPDF-settings.txt before clearing SessionData.
• Use a fresh temporary configuration before reinstalling.

Stop changing settings as soon as two local test documents return after a clean exit and restart. If only specific documents remain unavailable, troubleshoot their paths, permissions, synchronization state, or format support instead.

7. Frequently Asked Questions

7.1 Why Does SumatraPDF Remember My Page but Not Reopen My Tabs?

Remembering a document and its viewing position is not the same as restoring the complete application session. Tab restoration depends on RestoreSession and valid saved SessionData. Use two documents to test the session rather than relying on the page position of one file.

7.2 Where Is SumatraPDF-settings.txt Located?

An installed copy normally uses a SumatraPDF folder under the current user's local application data directory. A portable copy normally stores the file next to its executable. The most dependable method is to open advanced settings from within the exact copy you use, especially if multiple copies are installed.

7.3 Why Does Session Restore Work From One Shortcut but Not Another?

The shortcuts may launch different executables, use different settings locations, or include different command-line options. Compare their Target fields. Also check whether a file association opens an installed copy while your desktop shortcut opens a portable copy.

7.4 Will Deleting the Settings File Fix Session Restore?

It can fix corruption, but it also resets unrelated preferences and removes the saved session. Rename or back up the file first. A better initial step is to test with a fresh configuration or carefully reset only bad SessionData.

7.5 Why Was My Latest Session Not Saved?

The application may not have exited cleanly, the settings location may not be writable, or a cleanup or security tool may have removed or blocked the update. Test persistence by changing one harmless preference, closing normally, and checking whether the change remains after restart.

7.6 Do Ghostscript or Printer Drivers Control Session Restore?

No. Those components can matter to particular PostScript, conversion, rendering, or printing workflows, but they do not normally control whether PDF tabs reopen. If a tab returns but the document does not display or print correctly, treat that as a separate format, rendering, or printing problem.