It needs to be completely off
After learning that you can easily export screenshots from the Nintendo Switch in bulk to the PC with a microSD card (and adapter, which is included in nearly every card these days), I just had to try it out. The thing is, I didn’t think to turn the Switch completely off, and obtained an error message that instructed me to never remove the card unless the system was shut off entirely.
For the past few weeks, I’ve basically never turned my Switch off. I keep it in sleep mode and just pop it out of the dock or detach the Joy-Con and play immediately on the TV. It’s convenient, but if you’re going to do some aforementioned screenshot dumps, make sure you do it right. Just hit the power button on the top left, then select “Power Options,” then shut it off.
It’s a small little obvious PSA for sure, but an important one! Once you start accruing more data on your SD card (which should happen fast as the default HDD space is woefully small) it would be a shame to have it corrupted.