GCP static website hosting via bucket does not serve configured error and index pages

I'm trying to serve a simple static React SPA through GCP bucket as described here: https://cloud.google.com/storage/docs/hosting-static-website

It is crucial for my structure that for /my_directory, the file /my_directory/index.html is served.

I think what I want is exactly described here in the "Three-object bucket" in the documentation

This is my config:

This is my file structure:

In the folder test_2023_11_03_c there is a file "index.html"

But it doesn't work.

For

• https://storage.googleapis.com/my-bucket-name, I expect to get the main index.html served. However, instead I get a list of all files in the bucket.
• https://storage.googleapis.com/my-bucket-name/something-that-doesnt_exist, I expect the content of my_error.html to be served. However, instead I get <?xml version='1.0' encoding='UTF-8'?><Error><Code>NoSuchKey</Code><Message>The specified key does not exist.</Message><Details>No such object: my-bucket-name/something-that-doesnt_exist</Details></Error>
• https://storage.googleapis.com/my-bucket-name/test_2023_11_03_c, I expect the content of the directory's index.html to be served. However, instead I get the same error: <?xml version='1.0' encoding='UTF-8'?><Error><Code>NoSuchKey</Code><Message>The specified key does not exist.</Message><Details>No such object: my-bucket-name/test_2023_11_03_c</Details></Error>

What am I doing wrong?

You are trying to access files without a custom domain. Hence, You are experiencing this behavior. It is stated in the documentation that:

The MainPageSuffix and NotFoundPage website configurations are only used for requests that come to Cloud Storage through a CNAME or A redirect. For example, a request to www.example.com shows the index page, but an equivalent request to storage.googleapis.com/www.example.com does not.

Thus, API behavior for requests to Cloud Storage domains, such as storage.googleapis.com/www.example.com, is preserved. For example, you can continue to list objects in the www.example.com bucket as you would for any other bucket. In the case of the www.example.com bucket, the object listing you receive includes 404.html and index.html

Also check this document to set a website configuration for a bucket.