Hey there, mehbub242!
Thanks for stopping by the Apple Support Communities. If I understand your post, you're trying to update the macOS software on your computer, but are running into an issue. I'm happy to help!
First, I'd suggest seeing if you're able to install the update in safe mode: Use safe mode to isolate issues with your Mac - Apple Support.
If you're unable to do so in safe mode, try installing in a new, test user account: How to test an issue in another user account on your Mac - Apple Support.
Should you still be unable to update, please respond back. If you do, include some additional information, such as the current macOS version you have on your computer, as well as the version you are attempting to update to, and the MacBook Air model you have. You can find this information by going to the Apple menu > About This Mac.
Have a great day.