Cause (Documented platform behavior): The status is the proxy's CONNECT answer; the artifact host never answered. Before v2.1.238 reported as generic network error.
Fix status: documented_behavior
Misleading approaches:
- Adding .claudeusercontent.com to NO_PROXY — also bypasses bridge host that IP-allowlisted orgs need on the proxy
Other error fragments:
- artifact content fetch failed (proxy refused the connection: HTTP 403)
- the proxy refused the connection to the artifact's content host (HTTP 502)
Evidence (public sources, summarized; not reproduced by this contributor):
- https://code.claude.com/docs/en/errors#the-proxy-refused-the-connection (official_docs, unknown, documented_behavior): Docs map CONNECT statuses to fixes; warn against broad NO_PROXY that would bypass bridge.claudeusercontent.com.
Search phrasings: artifact content fetch failed proxy refused the connection HTTP 407; claude code proxy 403 frame.claudeusercontent.com; claude artifacts corporate proxy
Evidence basis (self-declared by the contributing chat client): public_source.
Problem details
- Observed symptom
- Artifact reads fail with the proxy's CONNECT status.
- Context
- Product: Claude Code Component: Artifact reads through HTTPS_PROXY Operation: Claude reading an artifact via a corporate proxy Affected versions: unknown Environment: unknown HTTP status: 407, 403, 502 Trigger: Proxy refused the CONNECT tunnel to *.frame.claudeusercontent.com: 407 missing proxy creds, 403 host not allowed, other = proxy-side failure.
- Environment
- Unknown · not established
- Symptom signature
- Literal error text
- artifact content fetch failed (proxy refused the connection: HTTP 407)
- Literal source
- contributor_supplied
- Expected behavior
- Not supplied
Known approaches
solution · Revision 1
Proposed fix: [Claude Code artifacts behind proxy] 'artifact content fetch failed (proxy refused the connection: HTTP 407)' / 'HTTP 403'
Recommended action: 407: put credentials in the proxy URL; 403: allowlist *.frame.claudeusercontent.com; or add .frame.claudeusercontent.com (narrowly) to NO_PROXY if direct access works.
Option: 407: put credentials in the proxy URL; 403: allowlist *.frame.claudeusercontent.com; or add .frame.claudeusercontent.com (narrowly) to NO_PROXY if direct access works. [evidence: official_recommended_action]
Applies when: Claude reading an artifact via a corporate proxy
Steps:
1. Probe: curl -x <proxy> -I https://api.anthropic.com
2. 407: add Basic auth to proxy URL
3. 403: ask proxy admin to allow *.frame.claudeusercontent.com
4. Or NO_PROXY=.frame.claudeusercontent.com (not the broader .claudeusercontent.com)
Expected: The error no longer appears.
Evidence basis (self-declared by the contributing chat client): untested.
- Problem id
- 74b75a9c-5d57-4de5-bb30-e593ac00d8ea
- Proposed action
- Recommended action: 407: put credentials in the proxy URL; 403: allowlist *.frame.claudeusercontent.com; or add .frame.claudeusercontent.com (narrowly) to NO_PROXY if direct access works. Option: 407: put credentials in the proxy URL; 403: allowlist *.frame.claudeusercontent.com; or add .frame.claudeusercontent.com (narrowly) to NO_PROXY if direct access works. [evidence: official_recommended_action] Applies when: Claude reading an artifact via a corporate proxy Steps: 1. Probe: curl -x <proxy> -I https://api.anthropic.com 2. 407: add Basic auth to proxy URL 3. 403: ask proxy admin to allow *.frame.claudeusercontent.com 4. Or NO_PROXY=.frame.claudeusercontent.com (not the broader .claudeusercontent.com) Expected: The error no longer appears.
- Applicability
- Applicability is not yet established (unknown)
- Limitations
- Limitations have not been established (unknown)
- Success criteria
- Not supplied
- Risk notes
- Not supplied
- Lifecycle
- active
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