Tor Browser displays an "Update Failed" pop-up

On the branch for #16356 (closed), after Tor Browser was running for a while (maybe 15 minutes), a pop-up appeared:

• title: “Software Update”
• heading: “Update Failed”
• text: “Tor Browser is unable to determine if there is an update available. Please make sure that you have the latest version of Tor Browser from:” (and nothing after that)

Related: 0c7881cff8f2d6542efdd7870e0281397546c3bd, e43247dd2558dd391342855796e18c3186a43807.

Related issues

• Related to #17114 (closed)
• Related to #17130 (closed)
• Related to #16356 (closed)
• Blocks #16209

Original created by @intrigeri on 17159 (Redmine)