Big Sur 11.6
Why can't I download on my MacBook Air
MacBook Air 13″, macOS 11.3
Why can't I download on my MacBook Air
MacBook Air 13″, macOS 11.3
Since you're already running 11.3, you should be able to update to 11.6. Check if this helps If an error occurred while updating or installing macOS - Apple Support
Since you're already running 11.3, you should be able to update to 11.6. Check if this helps If an error occurred while updating or installing macOS - Apple Support
Big Sur 11.6