If you're using sky3ds+ then download sd formatter v4 and format your sd card (full format - overwright and automatic size adjustment enabled in settings). And try again.
Alos, I hope you are not using Kingston sd card.
Does this still work?
http://crediar.no-ip.com/sp.php
My 3ds has stopped receiving streetpass since yesterday :(
And i don't have fancy modem and rooted phone so this was my only option. :(
This is some big ass update.. I'm still waiting to download it...
So now we know that 3DS downloads updates in the background and then when you accept it, it just installs, that is why it was so speedy for you...
Actually in the past updates there was no word "may" in that sentence, but instead was "WILL render the system permanently unplayable"
They are getting soft
I tried everything, but my battery is the same as before update (about 2 days in sleed mode).. Anyway new update is out v2.1.0 maybe this fixes problem foy you?