warpdotdev
Warp IDE does NOT have User-Agent header set when connecting to remote mcp servers
Pre-submit Checks
- [x] I have searched Warp bugs and there are no duplicates
- [x] I have searched Warp known issues page and my issue is not there
- [ ] I have an issue with AI and have included the debugging ID (Optional, but helps expedite the AI quality fix). Debugging ID intructions
- [x] I have technical issue and have included the logs (optional, but helps expedite the bug fix). Log intructions
Describe the bug
After configuring our remote MCP server hosted in AWS (behind load balancer), it failed to connect (got 403 error). After some debugging, it turns out Warp IDE didn't send the request with User-Agent header set, and hence blocked by our AWS ACLs.
To reproduce
Configure and connect a remote MCP server (which has ACL that blocks request without User-Agent header)
Expected behavior
It should connect to the remote MCP server successfully.
Screenshots, videos, and logs
2025-09-15 11:00:37.591 | [error] MCP: preflight connection to MCP server failed: Transport creation error: HTTP status client error (403 Forbidden) for url (https://mcp.aci.dev/gateway/mcp?bundle_id=f7bexxxx-xxxx-xxxx-xxxx-xxxx2229a)
Operating system (OS)
macOS
Operating system and version
15.6.1
Shell Version
No response
Current Warp version
v0.2025.09.10.08.11.stable_01
Regression
No, this bug or issue has existed throughout my experience using Warp
Recent working Warp date
No response
Additional context
No response
Does this block you from using Warp daily?
Yes, this issue prevents me from using Warp daily.
Is this an issue only in Warp?
Yes, I confirmed that this only happens in Warp, not other terminals.
Warp Internal (ignore): linear-label:b9d78064-c89e-4973-b153-5178a31ee54e
None
Warp supports SSE and Token or OAuth for MCP servers https://docs.warp.dev/knowledge-and-collaboration/mcp. Try again on the latest version to see if this issue persists.
