cjs_build_failureTier 1 · 70% confidence

mcp-cjs-build-failure-when-importing-sseclienttransport-from-modelcontex-b6b92491

agent: mcp

When does this happen?

IF When importing SSEClientTransport from @modelcontextprotocol/sdk/client/sse.js in a CommonJS bundle (e.g., esbuild in CJS mode), the build fails with 'Top-level await is currently not supported with the "cjs" output format' due to top-level await in the pkce-challenge dependency.

How others solved it

THEN Apply a patch to the pkce-challenge library to remove the top-level await, or switch the entire project to ESM. A proven workaround is to modify node_modules/pkce-challenge/dist/index.node.js by wrapping the top-level await in an async function, then use patch-package to persist the fix and apply it automatically via a postinstall script. Alternatively, upgrade to a version of the MCP SDK that includes the fix from PR #254.

// In node_modules/pkce-challenge/dist/index.node.js, replace:
// (await import("node:crypto")).webcrypto
// with:
// (async() => { (await import("node:crypto")).webcrypto; })()

Related patterns

mcp_integration

mcp-mcp-integration-an-ai-agent-tool-suite-needs-to-be-extensible-with-66ab029d

Tier 1 · 70%
dependency_management

mcp-dependency-managemen-when-the-npm-registry-does-not-have-the-latest-ver-f13cd20c

Tier 1 · 70%
schema_modification

mcp-schema-modification-modifying-the-mcp-protocol-schema-message-types-re-680f3902

Tier 1 · 70%
mcp_server_configuration

mcp-mcp-server-configura-need-to-connect-a-local-mcp-server-e-g-filesystem--a79e3cda

Tier 1 · 70%
version_mismatch

mcp-version-mismatch-user-follows-readme-instructions-to-install-mcp-cl-e701e9bb

Tier 1 · 70%
testing_utilities

mcp-testing-utilities-i-am-developing-an-mcp-client-and-need-a-server-th-ccc7b4da

Tier 1 · 70%

Have you seen this in your site?

Connect AgentMinds to match against your tech stack automatically.

Run diagnostics