How to Update Silverlight on Safari: Step-by-Step Browser Fix

Silverlight on Safari can feel like maintaining a vintage ThinkPad—doable but increasingly unnecessary. I still get questions about it from folks running legacy systems at our Five Points tech center.

The update process is straightforward if you know where to look. You’ll need the latest Silverlight installer from Microsoft’s archive, admin rights, and 5 minutes of patience. Safari’s plugin settings require a quick toggle most users miss.

This works for macOS up to Catalina and older Windows versions. Newer systems should consider modern alternatives, but for that one legacy app you can’t Replace, this keeps it running.

Between you and me, I keep a dedicated test machine for these cases. Works every time when you follow the exact steps.

What Youll Need

Instructions

Here’s how I consistently get this working without browser conflicts or compatibility issues.

Open Safari and navigate to about:plugins in the address bar. Scroll to find the Microsoft Silverlight entry and note the current version number. If it’s not listed, the plugin is either disabled or not installed.

Confirm Safari supports NPAPI plugins by checking Safari > Preferences > Security. The Allow Plug-ins option must be enabled. This is the first checkpoint—without this, the update won’t take effect.

Visit the official Microsoft Silverlight download page using any browser. Avoid third-party sites, as they often bundle adware. Select the Mac OS X version, even if you’re updating for Safari specifically.

The installer is a .dmg file. Download it to your Downloads folder and verify the file size matches Microsoft’s listed size (typically ~6MB). A mismatch indicates a corrupted download.

Mount the .dmg file and run the installer. Follow the prompts, accepting the license agreement. The installation completes silently—there’s no progress bar, but the process takes 10-15 seconds.

Quit Safari completely (⌘Q) before reopening it. This ensures the browser reloads with the new plugin. Reopen Safari and return to about:plugins to confirm the version updated.

Go to Safari > Preferences > Websites > Plug-ins. Find Silverlight in the list and set it to On for all websites or just trusted sites. This step is often overlooked but critical for functionality.

Test the update by visiting a site known to use Silverlight, like Netflix’s older movie player (if available) or Microsoft’s Silverlight test page. The content should load without prompts for additional installations.

If Silverlight content fails to load, clear Safari’s cache via Safari > Clear History and select all history. Then, restart the browser again. This removes any cached old plugin data.

For persistent issues, check Console.app in Utilities for errors related to Silverlight. Common fixes include resetting Safari’s preferences or reinstalling the plugin after a full system restart.

Tips and Common Mistakes

These practical insights will help you avoid common pitfalls during the update process.

Version Verification: In Step 1, pay close attention to the version number display. Safari on macOS strictly caps at version 5.1.50918.0, so attempting to install anything newer will fail due to Apple’s NPAPI deprecation. This is a hard limitation, not a user error.

File Size Check: When downloading in Step 2, confirm the installer is 6-7 MB—this is the definitive size for the correct Mac OS X package. Smaller files likely indicate corrupted downloads, while larger ones may contain bundled adware from untrusted sources.

Installation Timing: The Step 3 installation should complete in under 2 minutes as specified. If it stalls, don’t interrupt the process—wait for the confirmation dialog. Forcing a restart mid-installation can corrupt the plugin files, requiring a full uninstall before retrying.

Testing Protocol: During Step 4, resist the urge to test in private browsing mode—it blocks plugins by default on Safari. Always test in a standard window, and if Netflix videos don’t start within 5-10 seconds, clear the cache as instructed before assuming the update failed.

Frequently Asked Questions

Updating Silverlight on Safari is straightforward once you follow the right steps. Always ensure compatibility and check for the latest version to avoid issues. If you run into problems, revisit the FAQs or Microsoft’s support page for extra help. Happy browsing! 🌟