Hello to all! May be somebody met such a problem. I develop app for Mac using standard Cocoa. It's sandboxed with entitlements: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "...w.apple.com/DTDs/Pr..."> <plist version="1.0"> <dict> <key>com.apple.security.app-sandbox</key> <true/> <key>com.apple.security.files.user-selected.read-write</key> <true/> <key>com.apple.security.network.client</key> <true/> <key>com.apple.security.network.server</key> <true/> </dict> </plist> I distribute the app via dmg files or .app (Developer ID) without Mac app store). Also I use Sparkle project 2.x for an autoupdate (big thanks to guys for their work). The problem: some our users complain about none of WKWebView load after the first installation of the application - interface become not responding. The same applies to Sparkle - simply UI becomes unresponsive and some time later Mac OS shows "Application not responding" - it also uses WKWebView for html what's new (how I understand). And this problem exists until user restart his Mac. However, they do not have antivirus software installed and simple URLSessions work well. This problem only with WKWebView. I notarise all the app files as well as notarise dmg files. Thank you for your help! (Probably the problem only take place macos Big Sur. There have been no problems on Catalina yet)