This is the folder structure of my app
.idea .vscode android build fonts Oxygen-Bold.tff Oxygen-Light.tff Oxygen-Regular.tff images pizza0.png pizza1.pn
After declaring correctly in pubspec.yaml, consider giving full path of the image ex.
'assets/images/about_us.png'
instead of just images/..
images/..
worked for me after wasting 2 hours on such a trivial error.