July 31, 2021

I recently went to get a COVID-19 test at a large medical facility. When I showed up without an appointment, I learned they use ZocDoc for making appointments. So, I scanned a QR code they gave me and my phone ended up at the ZocDoc website.

Which hung.

The person helping me suggested a switch from the 4G on my phone to their Wi-Fi. It didn't help.

Two people helped me get registered and each had no idea what the problem could be. Apparently the ZocDoc system works fine for everyone else. Thankfully, they had a paper based system to fall back on.

That I was the only one with a ZocDoc problem was a hint, but it took me a while to get it.

Being a Defensive Computing kind of guy, links on my Android phone do not open in Chrome, they open in Firefox Focus, which blocks ads and trackers. It wasn't until I was done with the paper registration, and waiting my turn, that the light bulb went off in my head - the ad/tracker blocking was causing the problem.

As you see below, Firefox Focus shows you how many ads/trackers it has blocked on the page and even suggests that "Turning this off may fix some site problems". Indeed. With blocking disabled, the ZocDoc site loaded just fine.

 Firefox Focus suggests disabling blocking 

Every coin has two sides.