Can Pokemon GO's friend list error be fixed?

​A common "friend list error" has been affecting many Pokemon GO players, and it can be an incredibly frustrating experience.

I keep trying to send a friend request on pokémon go but it keeps saying error, how do I fix this? - Quora

How to fix Pokemon Go friends list glitch and stop it disappearing - Dexerto

Anyone else having issues with their friends list and fitness metrics? : r/pokemongo

How to Fix Unable to Authenticate Error in Pokemon GO - Prima Games

Pokémon Go Referral Program: Rewards and how to find and use Referral Codes explained

49 Hidden Tips for Pokemon Go Fanatics

How to fix Modern Warfare 2 “failed fetching crossplay friends list” error - Charlie INTEL

How Pokemon Go Update's New Trading And Friends Systems Work - GameSpot

Half my time spent on PoGo is me just staring at this screen. I know it's a known glitch but it's been months with no fix so deserves its own thread because

Pokémon Go' Friendship Levels Not Increasing, Players Claim; Here's The Workaround

I keep trying to send a friend request on pokémon go but it keeps saying error, how do I fix this? - Quora