Site Verification API returns 503 backendError when using webResource().insert() with DNS method

[rafaramos]

Environment details

• OS: Windows 11
• Python version: 3.13.3
• pip version: Latest
• google-api-python-client version: 2.167.0

Steps to reproduce

1. Enable Site Verification API on project.

2. Create a service account with Owner role.

3. Authenticate using credentials.json.

4. Use webResource().getToken() to generate a DNS token — works correctly.

5. Publish the TXT record:
   google-site-verification=DGSSxFEFCIoxdzjc1imgSz1ttICLTzkMeFJGWOmxkog

6. Confirm visibility of TXT record using Google's DIG tool, OpenDNS, and global resolvers.

7. Call webResource().insert() with type INET_DOMAIN and verificationMethod='DNS'.

Expected behavior

Should verify domain successfully when the TXT token is present.

Actual behavior

Always returns 503:

HttpError 503 when requesting https://www.googleapis.com/siteVerification/v1/webResource?verificationMethod=DNS&alt=json returned "An unexpected error occurred. Please try your request again."

This issue has persisted for over 24 hours. It is not a 403 or 400 — it’s a backend error from the Site Verification service.

Additional context

• Domain: soyrafaramos.com
• TXT record is globally visible
• Token is freshly generated and matches the request
• All IAM and API settings are correct
• Verified via script and manual tools

Is this API endpoint currently degraded or subject to temporary failure?

Thanks in advance.