Browsers won't clear cache for some pages

The issue is almost certainly stale cached content that is not being fully cleared on the affected devices, especially in Microsoft Edge/WebView-based scenarios.

Try the following steps in order on a Windows device using Edge, then repeat similar steps on Chrome/Safari:

1. Clear Edge cache thoroughly
   1. In Edge, go to edge://settings/clearBrowserData.
   2. Time range: select All time.
   3. Select at least Cookies and other site data and Cached images and files.
   4. Select Clear now.
   5. Close all Edge windows, then reopen Edge and reload the site.
2. Test in InPrivate / Incognito mode
   1. Open an InPrivate window in Edge (Ctrl+Shift+N) or Incognito in Chrome.
   2. Browse to the site.
   3. If the updated pages show correctly in InPrivate/Incognito but not in a normal window, the problem is cached data, cookies, or extensions in the normal profile. Continue with the next steps.
3. Disable extensions temporarily
   1. In Edge/Chrome, disable all extensions (especially ad blockers, privacy/anti‑tracking, or security add‑ons).
   2. Restart the browser and test the site again.
4. Force no-cache headers on the site (for future changes) If this is a site that is being developed or updated frequently, configure the web server to send headers that prevent aggressive client caching for static files (HTML, CSS, JavaScript) during development. For example, add these headers to responses for static content:
   • Cache-Control: "private, no-cache, no-store"
   • Pragma: "no-cache"
   • Expires: "-1"
   For IIS, a web.config snippet for static content can look like:

      <system.webServer>
        <staticContent>
          <clientCache cacheControlMode="UseMaxAge" cacheControlMaxAge="0.00:00:00" cacheControlCustom="must-revalidate" />
        </staticContent>
      </system.webServer>
   

   This ensures that when pages are updated, browsers are forced to re-download them instead of using stale cached versions.
5. If using Office/Outlook or embedded views If the site is being viewed inside an Office add-in or Outlook (which uses Edge WebView), there can be an additional Office-specific cache. In that case, use Microsoft Edge DevTools attached to the WebView and use Clear cache from the Network tab, as described in the Office add-ins cache guidance.
6. iPhone (Safari / Edge on iOS)
   1. In iOS Settings → Safari, clear History and Website Data.
   2. For Edge on iOS, ensure tracking prevention isn’t blocking necessary cookies (Settings → Edge → Allow Cross‑Website Tracking if applicable) and then clear browsing data from within Edge.

If the site always shows correctly for other people and in InPrivate/Incognito, but not in a normal session even after clearing cache and cookies, the remaining causes are almost always:

• A browser profile sync restoring old cached data or service worker state.
• A proxy, security, or content-filtering product caching pages on the device or network.

Testing on a different network (e.g., mobile hotspot) and a fresh browser profile can help confirm that.

References:

• Troubleshoot development errors with Office Add-ins
• Clear the Office cache
• What to do if Microsoft Edge isn't working
• Error occurs when trying to open Dynamics 365 App for Outlook
• Troubleshooting startup or sign-in issues for Power Apps
• Microsoft 365 Admin Center not loading - Microsoft Q&A
• Problem Viewing thread. - Microsoft Q&A