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.

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

Pokemon Go error: 'Failed to get Friends list' - how to fix the problem, UK, News

Bug] “Error 0 : Failed to get Friend List. Try Again later.” Happens anytime I open any friend gift, still get gift items though. : r/TheSilphRoad

Pokémon Go update: trading Pokémon and friends list - Polygon

Pokemon Go Error code 99313 Why can't I battle my friends remotely? - GameRevolution

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 The Friend Bug In Pokemon GO!

Can Pokemon GO's friend list error be fixed?

Help I can't access my friends list in Pokémon go : r/pokemongo

What is 'Error 6' in Pokemon Go, and how do I fix it? - Quora