[BUG] API Connection Error with Google Vertex AI - Continuous Retry Loop

Bug Report

---
name: Bug report
about: Claude Code is not working after upgrading to v1.0.38
title: '[BUG] API Connection Error with Google Vertex AI - Continuous Retry Loop'
labels: bug
assignees: ''
---

Environment

• Platform (select one):
• [ ] Anthropic API
• [ ] AWS Bedrock
• [x] Google Vertex AI
• [ ] Other: <!-- specify -->
• Claude CLI version: v1.0.38
• Operating System: macOS 15.5
• Terminal: Terminal App

Bug Description

The Claude CLI is experiencing persistent connection errors when attempting to communicate with Google Vertex AI API. The application enters a retry loop showing "API Error (Connection error.) · Retrying in 1 seconds… (attempt 1/10)" but fails to establish a successful connection.

Anthropic Python SDK is working fine same using Google Vertex AI settings, just Claude Code CLI is failing.

Steps to Reproduce

1. Configure Claude CLI to use Google Vertex AI as the platform
2. Execute any claude command that requires API communication
3. Observe the connection error and retry attempts
4. Wait for the retry cycle to complete

Expected Behavior

The Claude CLI should successfully connect to the Google Vertex AI API and execute the requested command without connection errors.

Actual Behavior

• The CLI displays "API Error (Connection error.)"
• Automatic retry mechanism activates with "Retrying in 1 seconds… (attempt 1/10)"
• Connection continues to fail on subsequent retry attempts
• Command execution is blocked due to connection issues

Additional Context

• This issue appears to be specific to Google Vertex AI platform integration
• The error suggests a network connectivity or authentication problem
• May be related to API endpoint configuration, credentials, or network restrictions
• Consider checking:
• Google Cloud authentication setup
• Network connectivity to Vertex AI endpoints
• API quotas and rate limits
• Regional availability of Vertex AI services

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