from fastapi import Request, Response from nicegui import Client, app, ui @app.exception_handler(404) async def exception_handler_404(request: Request, exception: Exception) -> Response: with Client(ui.page('')) as client: with ui.column().style('width: 100%; padding: 5rem 0; align-items: center; gap: 0'): ui.label('Sorry').style('font-size: 3.75rem; line-height: 1; padding: 1.25rem 0') ui.label('Something went wrong.').style('font-size: 1.25rem; line-height: 1.75rem; padding: 1.25rem 0') ui.label('Please contact the server administrator at change@this.com for additional support.').style( 'font-size: 1.125rem; line-height: 1.75rem; color: rgb(107 114 128)') return client.build_response(request, 404) ui.link('Go to nonexisting page', '/nonexisting') ui.run()