Hmbown/CodeWhale · error · anyhow::Error

Invalid MCP URL

Error message

Invalid MCP URL

What it means

Remote entries supply a `url` string parsed with reqwest::Url::parse; if the string is not a parseable URL at all, this error is thrown before any scheme/host checks. The bad URL's contents are not echoed.

Solutions

1. Add an explicit scheme: `https://mcp.example.com` or `http://localhost:3000`
2. URL-encode or remove stray spaces and characters from the value
3. Test the string in a URL parser before saving the config

Example fix

// before
{"mcpServers":{"api":{"url":"mcp.example.com:8080"}}}
// after
{"mcpServers":{"api":{"url":"http://mcp.example.com:8080"}}}

try { new URL(u); } catch { throw new Error(`not a URL: ${u}`); }

function isParseableUrl(u) { try { new URL(u); return true; } catch { return false; } }

catch, then run the string through a URL parser locally to see the real parse error

When it happens

Trigger: `url` is missing the scheme ("mcp.example.com/sse"), contains spaces, or is otherwise malformed so Url::parse fails.

Common situations: Omitting `https://` when copying a server address; trailing quotes or whitespace pasted into the field; using a bare host:port for a local dev server.

Understand the failure class

Background: "Invalid URL" errors: why new URL(), URI.parse, and reqwest::Url reject your string — missing scheme, whitespace, and bad path format — this error's family across 39 libraries.

Related errors

• MCP HTTP requires an http:// or https:// URL with a host
• MCP server URL ' ' must include a host
• reviewed plugin MCP endpoint has an unsafe origin
• Unsupported MCP URL
• bad_target

AI-assisted analysis of Hmbown/CodeWhale@73e0f67d83 (2026-09-22). Data as JSON: /api/errors/c59ffef4941479c3. Report an issue: GitHub.

Appendix: source

Thrown at crates/tui/src/mcp/external_import.rs:208

                    .is_some_and(|map| map.keys().all(|key| key == "client_id")),
                "Source contains unsupported OAuth fields"
            );
        }
        let server: McpServerConfig = serde_json::from_value(config)
            .map_err(|_| anyhow::anyhow!("Invalid MCP entry; contents omitted"))?;
        anyhow::ensure!(
            server.command.is_some() != server.url.is_some(),
            "MCP entry must have one target"
        );
        if let Some(command) = &server.command {
            anyhow::ensure!(
                !command.trim().is_empty() && !command.chars().any(char::is_control),
                "Invalid MCP command"
            );
        }
        if let Some(url) = &server.url {
            let parsed =
                reqwest::Url::parse(url).map_err(|_| anyhow::anyhow!("Invalid MCP URL"))?;
            anyhow::ensure!(
                matches!(parsed.scheme(), "http" | "https")
                    && parsed.host_str().is_some()
                    && parsed.username().is_empty()
                    && parsed.password().is_none(),
                "Unsupported MCP URL"
            );
        }
        super::validate_mcp_transport(server.transport.as_deref())
            .map_err(|_| anyhow::anyhow!("Unsupported MCP transport"))?;
        let hard_blocked = !server.is_enabled();
        out.push(ImportCandidate {
            summary: server_summary(&name, &server),
            name,
            source_kind: kind.clone(),
            source_path: path.to_path_buf(),
            content_hash: hash.clone(),
            hard_blocked,

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