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claude-code - 💡(How to fix) Fix Linear MCP save_issue triggers persistent Cloudflare block after burst of parallel requests [1 participants]

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anthropics/claude-code#55521•Fetched 2026-05-03 04:51:13
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After making a burst of parallel save_issue calls via the claude.ai Linear MCP integration, the MCP proxy IP gets blocked by Cloudflare. The block persists indefinitely — it has not self-healed after 12+ hours and multiple session restarts.

Error Message

Streamable HTTP error: Error POSTing to endpoint:

<!DOCTYPE html> <title>Attention Required! | Cloudflare</title> ... <h1>Sorry, you have been blocked</h1> <h2>You are unable to access anthropic.com</h2>

Root Cause

After making a burst of parallel save_issue calls via the claude.ai Linear MCP integration, the MCP proxy IP gets blocked by Cloudflare. The block persists indefinitely — it has not self-healed after 12+ hours and multiple session restarts.

Fix Action

Workaround

None found. The block appears to be on the Anthropic MCP proxy infrastructure's IP(s) rather than being session- or user-specific, so there is no client-side workaround available.

Code Example

Streamable HTTP error: Error POSTing to endpoint:
<!DOCTYPE html>
<title>Attention Required! | Cloudflare</title>
...
<h1>Sorry, you have been blocked</h1>
<h2>You are unable to access anthropic.com</h2>
RAW_BUFFERClick to expand / collapse

Description

After making a burst of parallel save_issue calls via the claude.ai Linear MCP integration, the MCP proxy IP gets blocked by Cloudflare. The block persists indefinitely — it has not self-healed after 12+ hours and multiple session restarts.

Steps to reproduce

  1. Use the mcp__claude_ai_Linear__save_issue tool to create Linear issues
  2. Send a burst of 5–7 parallel save_issue calls in a single response (as the model naturally does when creating independent issues in parallel)
  3. Some calls in the burst succeed; subsequent calls begin returning Cloudflare 403 blocks
  4. All further save_issue calls fail with the same Cloudflare block — including in new sessions started hours or days later

Error response

Every subsequent call returns an HTML Cloudflare block page instead of a JSON response:

Streamable HTTP error: Error POSTing to endpoint:
<!DOCTYPE html>
<title>Attention Required! | Cloudflare</title>
...
<h1>Sorry, you have been blocked</h1>
<h2>You are unable to access anthropic.com</h2>

Details

  • MCP server: claude.ai Linear (mcp__claude_ai_Linear__save_issue)
  • Affected operation: save_issue (create new issue)
  • Trigger: burst of ~7 parallel tool calls in a single model response
  • Observed proxy IPs blocked: 185.195.59.152, 86.137.238.98
  • Cloudflare Ray IDs (sampled): 9f511503efaa6d50, 9f5116b5eedf6d50, 9f5117122b6b6d50, 9f511bc729d44343, 9f512c664ae1d8a1, 9f513b6eed997733, 9f5550ac1c0cef46
  • Duration: block persists 12+ hours across multiple claude --resume sessions
  • Workspace: linear.app/nickwarters

Impact

Once triggered, the Linear MCP integration is completely non-functional for issue creation. The block survives session restarts and does not self-heal on any observed timescale.

In this specific case, 10 of 39 planned issues were successfully created before the block triggered. The remaining 29 issues cannot be created via the MCP and must be created manually.

Expected behaviour

Either:

  • The MCP proxy should not trigger Cloudflare WAF rules when making legitimate burst API calls to Linear, or
  • The MCP proxy IPs should be allowlisted / the requests rate-limited client-side before the burst reaches Cloudflare, or
  • The block should self-heal on a predictable short timescale (e.g. 5–10 minutes)

Workaround

None found. The block appears to be on the Anthropic MCP proxy infrastructure's IP(s) rather than being session- or user-specific, so there is no client-side workaround available.

extent analysis

TL;DR

Implement rate limiting on the save_issue calls to prevent triggering Cloudflare's WAF rules.

Guidance

  • Investigate the Cloudflare WAF rules to understand what triggers the block and adjust the save_issue call rate accordingly.
  • Consider implementing a delay between parallel save_issue calls to prevent bursts that trigger the block.
  • Verify if the MCP proxy IPs can be allowlisted with Cloudflare to prevent future blocks.
  • Review the claude.ai Linear MCP integration documentation to see if there are any recommended best practices for making parallel API calls.

Example

No code snippet is provided as the issue does not specify the programming language or implementation details.

Notes

The block persists indefinitely, suggesting that the issue is not with the client-side implementation, but rather with the MCP proxy infrastructure's IP(s) being blocked by Cloudflare. The solution may require coordination with the Anthropic MCP proxy infrastructure team and Cloudflare.

Recommendation

Apply a workaround by implementing rate limiting on the save_issue calls, as upgrading to a fixed version is not mentioned in the issue. This will help prevent triggering Cloudflare's WAF rules and reduce the likelihood of the block occurring.

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#api#memory management#API rate limit#retriever error#indexing error

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claude-code - 💡(How to fix) Fix Linear MCP save_issue triggers persistent Cloudflare block after burst of parallel requests [1 participants]