SumatraPDF PDF Background Stays White in Dark Mode: How to Fix It

You enable a dark interface in SumatraPDF, open a document, and the PDF page remains bright white with black text. This usually does not mean SumatraPDF is broken. The application interface theme and the colors used to render fixed-page documents are separate settings. The most likely causes are disabled color inversion, unchanged FixedPageUI colors, a scanned PDF made from images, settings that are not being saved, or Windows opening the file in a different SumatraPDF installation than the one you configured.

The steps below focus on the document canvas and page colors, not the menu or toolbar theme. Begin with a simple keyboard test, then check the relevant settings. Stop as soon as the PDF page becomes comfortably dark and the setting continues to work after restarting the reader.

1. Confirm the Symptom With Two Simple PDF Tests

Before editing configuration files, determine whether the problem affects every PDF or only a particular type of document. This distinction matters because a normal text PDF and a scanned image PDF can react differently to color inversion.

1.1 Test a normal text PDF

Open a simple PDF containing selectable black text on a white page. You should be able to drag across a sentence and copy the individual words. Avoid using a complex form, an illustrated manual, or a document with unusual page artwork for this first test.

With the PDF active, press Shift + I. In SumatraPDF, this shortcut toggles inverted colors for fixed-page content. If the page immediately becomes dark and the text becomes light, inversion was disabled. This is the quickest fix for the common “SumatraPDF PDF background stays white dark mode” symptom.

Press the shortcut only once and inspect the result. Pressing it twice returns to the original colors, which can make it appear that nothing changed.

Success looks like this: the formerly white page is dark, the text is readable, and page graphics are either inverted or adjusted with the rest of the rendered page. Close and reopen the PDF to see whether the preference persists. If it does, stop troubleshooting.

1.2 Compare it with a scanned PDF

Next, open a scanned PDF if you have one. A scanned document often consists of full-page photographs rather than independently rendered text and background elements. A quick way to identify one is to zoom in closely. Scanned letters may become visibly pixelated, and you may be unable to select individual words unless the file contains an OCR text layer.

Press Shift + I once while viewing this file. The entire page image may invert, producing light writing on a dark background, but photographs, stamps, diagrams, and paper discoloration may also become unnatural. In some files, the image may not produce the clean dark-reading appearance expected from a text PDF.

This comparison identifies the likely failure category:

• If the text PDF changes correctly, SumatraPDF inversion is working.
• If only the scanned PDF looks wrong, the source image is the limiting factor.
• If neither document changes, check InvertColors and the active settings file.
• If colors change and then reset, investigate settings persistence or multiple installations.

Do not repeatedly change unrelated Windows display settings if the normal text PDF responds correctly. At that point, the reader is functioning as designed, and the remaining difference comes from the scanned document’s image content.

2. Check the SumatraPDF Settings That Control Fixed Pages

SumatraPDF uses a group named FixedPageUI for PDFs and other fixed-layout formats. The important entries for this problem are TextColor, BackgroundColor, and InvertColors. These control document rendering separately from the colors of the application’s menus and toolbar.

2.1 Understand TextColor and BackgroundColor

TextColor specifies the preferred text color for fixed-page document rendering, while BackgroundColor specifies the preferred page background. A dark reading setup normally uses a light text color and a dark background color.

A representative custom configuration is:

FixedPageUI [
    TextColor = #e6e6e6
    BackgroundColor = #202020
    SelectionColor = #406080
    InvertColors = true
]

Your settings file can contain additional entries inside this group. Do not delete them merely because they are absent from the example. Change only the values needed for the page-color test.

Avoid pure black and pure white if strong contrast causes eye strain. A dark gray background such as #202020 with soft white text such as #e6e6e6 often produces a more comfortable result. These are preferences rather than required values.

2.2 Check InvertColors directly

InvertColors = true enables inverted rendering for fixed-page documents. InvertColors = false leaves their original colors in place. The Shift + I command toggles this behavior, so the file value may change after you use the shortcut and SumatraPDF saves its state.

If a PDF page stays white even though the application chrome is dark, confirm that the active FixedPageUI block contains:

InvertColors = true

Save the settings, return to the document, and reopen it if necessary. If the page turns dark, test another ordinary text PDF and restart SumatraPDF once. If the behavior persists, the fix is complete.

2.3 Keep selection highlights visible

A selection color that worked on a white page can become difficult to see against a dark background. If selected text appears invisible or the highlight blends into the page, adjust SelectionColor within the same FixedPageUI group.

Choose a medium color that contrasts with both the dark page and light text. After saving the change, drag across a sentence. A successful configuration leaves the selected words readable while making the selection boundary obvious.

This highlight issue does not mean that inversion failed. It is a secondary contrast problem created by the custom dark palette.

3. Rule Out File Associations and Document-Specific Factors

If settings appear correct but the result is inconsistent, verify that Windows is opening the intended executable and that the document is suitable for the test. Codecs, Ghostscript, printer drivers, and external converters are generally not relevant when an ordinary PDF opens correctly but its page remains white.

3.1 Verify the Windows file association

Windows may associate PDF files with a different SumatraPDF copy, especially if you have used both installed and portable editions. It may also open PDFs in a browser or another reader when you double-click them.

1. Open SumatraPDF directly from the shortcut or executable you configured.
2. Use its open command to load the test PDF.
3. Compare that result with double-clicking the same PDF in File Explorer.
4. If the results differ, check the default app assigned to the .pdf extension in Windows Settings.

Success looks like this: opening the file from inside SumatraPDF and from File Explorer produces the same dark page. Once both paths use the same reader, stop changing rendering settings.

3.2 Distinguish installed and portable settings

An installed SumatraPDF copy typically keeps its user settings in the user profile, while a portable copy can use a settings file associated with its portable location. If both copies exist, editing one settings file may have no effect on the other executable.

Open the exact SumatraPDF copy that exhibits the problem, then use its advanced settings command rather than searching the drive and editing the first similarly named file you find. This reduces the chance of changing an inactive configuration.

If the file is in a protected folder and SumatraPDF cannot write beside the portable executable, move the portable copy to a normal user-writable folder for testing. Do not grant broad administrator permissions merely to force a cosmetic setting to save.

3.3 Consider the source document

PDF pages can contain live text, vector artwork, transparency, photographs, scanned paper, or combinations of these. Inversion can therefore produce different results across files. A scanned page is one large image from the renderer’s perspective, even if it visually resembles black text on white paper.

Document permissions may restrict copying, annotation, or printing, but you should not attempt to bypass those restrictions. They are also not a reason to modify DRM or remove security controls just to obtain dark colors. Test a different, unrestricted PDF that you are permitted to use. If that document inverts correctly, the original file is document-specific.

Ghostscript may be relevant to PostScript workflows, and external codecs can matter for certain image formats, but neither is a normal fix for a PDF that already renders correctly in white. Likewise, changing a printer driver does not alter the on-screen FixedPageUI background. Investigate printing components only if the symptom occurs in printed or print-preview output rather than in the document viewer.

4. Inspect or Reset SumatraPDF-settings.txt Safely

If the shortcut works temporarily, settings revert after restart, or manual changes have no effect, inspect SumatraPDF-settings.txt. The safest route is to open advanced settings from within the affected SumatraPDF instance so you know that you are working with the relevant configuration.

4.1 Back up the current file

Before editing, close unnecessary documents and save a copy of the settings file with a clear name such as SumatraPDF-settings-backup.txt. The file can include history, display preferences, keyboard-related choices, and other customizations that you may want to restore.

Then locate the FixedPageUI block and check for these issues:

• InvertColors is set to false.
• BackgroundColor is still a light color.
• TextColor and BackgroundColor are nearly identical.
• There are accidental edits that damaged the block’s structure.
• You edited a settings file belonging to another SumatraPDF copy.
• The file or its directory is not writable by your Windows account.

Make one change at a time. Save the file, reopen or refresh the document, and record what happened. This approach makes it easy to reverse a bad color choice.

4.2 Reset without permanently deleting preferences

If the settings file appears damaged or contains years of uncertain modifications, close SumatraPDF and rename the file instead of deleting it. For example, rename it to SumatraPDF-settings.old.txt. Start SumatraPDF again and allow it to create a fresh configuration.

Test the normal text PDF, press Shift + I, and restart the application. If inversion now works and persists, the old configuration was likely conflicting with the expected behavior. Reapply only the custom settings you still need rather than copying the entire old file over the clean one.

If a fresh file does not solve the symptom, restore the backup if desired and proceed to a clean executable test. Repeatedly deleting settings is unlikely to help after a clean configuration produces the same result.

5. Run a Clean Temporary Test Before Reinstalling

Reinstallation is rarely the best first response to a white PDF background. A clean portable test can separate an executable problem from a configuration, association, or document problem without disturbing the installed copy.

1. Download SumatraPDF only from its official website.
2. Place a portable copy in a new user-writable folder.
3. Do not copy your existing settings into that folder.
4. Launch that executable directly.
5. Open one selectable-text PDF and press Shift + I once.
6. Open one scanned PDF and compare its behavior.
7. Close and restart the portable reader to test persistence.

Success looks like this: the text PDF changes to a dark page, remains readable, and retains the intended behavior after restart. If the clean copy succeeds, the installed application probably does not need reinstalling. Focus instead on the old settings file, folder permissions, shortcut target, or Windows file association.

If the clean copy fails only on the scanned PDF, the application is not necessarily malfunctioning. The scan’s image content is the likely explanation. If neither test file responds to Shift + I, confirm that the document window has keyboard focus and inspect the clean copy’s InvertColors setting.

6. Quick Fix Checklist

• Open a simple PDF with selectable text.
• Press Shift + I once to toggle inverted colors.
• Confirm that the page, not merely the menus, becomes dark.
• Check FixedPageUI for InvertColors = true.
• Set contrasting TextColor and BackgroundColor values if needed.
• Adjust SelectionColor if highlighted text is hard to see.
• Compare one text PDF with one scanned image PDF.
• Verify that Windows opens the same SumatraPDF copy you configured.
• Back up and rename the settings file if preferences do not persist.
• Use a clean portable test before reinstalling anything.

Stop when a selectable-text PDF displays with a dark page, readable light text, and persistent settings after restart. Continuing to change associations, drivers, or external tools after reaching that point can introduce unrelated problems.

7. Frequently Asked Questions

7.1 Why is the SumatraPDF interface dark while PDF pages remain white?

The interface theme and fixed-page document colors are separate. A dark menu or toolbar does not automatically guarantee an inverted PDF canvas. Toggle inversion with Shift + I or inspect InvertColors, TextColor, and BackgroundColor in the FixedPageUI settings.

7.2 What does Shift + I do in SumatraPDF?

It toggles color inversion for fixed-page document viewing. On a typical black-on-white text PDF, the page should become dark and the text light. Because it is a toggle, pressing the shortcut a second time restores the original appearance.

7.3 Why does a scanned PDF look strange in dark mode?

A scanned PDF usually contains photographs of pages rather than separately rendered text and background colors. Inverting the image can also invert photographs, stains, handwriting, and diagrams. Test a PDF with selectable text to confirm whether SumatraPDF’s inversion feature is working normally.

7.4 Can I create a custom dark theme for PDF pages?

Yes. Configure light TextColor and dark BackgroundColor values under FixedPageUI, enable InvertColors, and choose a visible SelectionColor. Test multiple ordinary PDFs because complex artwork can respond differently from plain text.

7.5 Why does the dark background disappear after restarting SumatraPDF?

The active settings file may not be writable, you may be launching a different installed or portable copy, or the configuration may be damaged. Open advanced settings from the affected executable, verify the file location, and test whether a renamed settings file allows a clean configuration to persist.

7.6 Should I reinstall SumatraPDF when inversion does not work?

Not immediately. First test Shift + I, inspect FixedPageUI, compare text and scanned PDFs, and verify the file association. A clean portable test is more informative than reinstalling because it isolates the existing configuration without deleting your preferences.