When i hosting my web app ,fat first attempt it loaded correctly,bute after some times, it shows some message like:

“Site Not Found
Why am I seeing this?
There are a few potential reasons:

You haven’t deployed an app yet.
You may have deployed an empty directory.
This is a custom domain, but we haven’t finished setting it up yet.
How can I deploy my first app?
Refer to our hosting documentation to get started.
“

and

also a email from google cloud

“Immediate action required: Critical problem with your Google Cloud Platform / API project”

i want to solve these problem and host my app