Error code 2021-0003 is displayed while using Nintendo Switch.
Updating the console to the latest system version will prevent this error from occurring.
What to Do:
Ensure your console has the latest system version.
If the console is already up to date, restart it by holding down the POWER Button for three seconds, then selecting "Power Options" > "Restart".
If the console does not respond, hold down the POWER Button for twelve seconds to force it to shut down, then power on the console again.
If the error is still occurring with downloaded software, check for corrupt data.
Situation Not Resolved:
If the issue persists, please contact our Customer Support.