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How to Fix Special Characters Missing in SharePoint HTML Previews
Question details
Users need to resolve an issue where special characters do not display correctly in SharePoint Online document previews.
- Product
- SharePoint Online
- Device & OS
- not provided
- Scenario
- Viewing previews of uploaded HTML files in a SharePoint Online document library.
- Observed behavior
- Special characters, accented text, and superscript characters display as unreadable replacement symbols in the preview pane, even though the files render perfectly after being downloaded.
Download the affected HTML file and open it locally in a web browser to confirm that the special characters render correctly before attempting to troubleshoot the SharePoint preview engine.
Verify and Update HTML Character Encoding
Ensure the HTML file explicitly declares UTF-8 encoding so SharePoint's preview engine can interpret special characters correctly.
SharePoint's online previewer relies on meta tags to determine how to render text. If the charset is missing, the preview engine defaults to standard ASCII, which corrupts special symbols.
Right-click your HTML file on your computer and open it with a text editor like Notepad or a code editor.
Locate the <head> section of your HTML document and add <meta charset="UTF-8"> right below it.
Click File > Save As, and ensure the 'Encoding' dropdown at the bottom of the save dialog is set to 'UTF-8' before saving.
Upload the newly saved file to your SharePoint document library and click on it to test the preview.
Open a Microsoft 365 Support Ticket
If the encoding is correct but the issue persists, escalate the rendering bug to Microsoft Support for investigation.
View and Edit Documents Locally with WPS Office
Avoid online rendering bugs and browser-based preview errors by managing your documents locally with WPS Office. As a free and lightweight alternative to Microsoft Office, it provides a stable environment for editing and viewing all your important files.
- 1. Download and Install: Visit the official WPS website, download the free desktop application, and follow the installation prompts.
- 2. Launch WPS Office: Open the application to access the all-in-one workspace for documents, spreadsheets, and presentations.
- 3. Open Your Files: Click 'Open' and select your downloaded documents to view and edit them locally, bypassing any online server rendering issues.
Frequently Asked Questions
Why do special characters turn into question marks or boxes in SharePoint?
This usually happens when the character encoding of the file (such as UTF-8) is not properly declared or recognized. As a result, the SharePoint preview engine misinterprets the data, substituting unrecognized characters with default symbols.
Does this preview issue affect the actual content of my uploaded files?
No, your original file remains perfectly intact on the server. The issue is strictly related to how SharePoint renders the document preview in your web browser. Downloading the file will show all special characters correctly.
What is a HAR log and why does Microsoft Support need it?
A HAR (HTTP Archive) log records the interactions between your web browser and the website. Support teams use it to track network requests and pinpoint exactly where the SharePoint preview rendering process is failing.
