How to fix mcporter 'Incompatible auth server: does not support dynamic client registration' with HubSpot MCP?

Question

Running `mcporter config login hubspot` against the remote HubSpot MCP server fails with "Incompatible auth server: does not support dynamic client registration". HubSpot's OAuth authorization server only supports `client_secret_post` and has no dynamic client registration endpoint, so the default login flow cannot start. The same error was reported for the Slack MCP server. How do you configure mcporter to use a pre-registered OAuth client instead?

AgentArmorHQ team · Accepted Answer

Fixed on main in commit dd33721; the thread does not name a released version, so use a build that includes that commit (or wait for the next release). The root cause: HubSpot's OAuth authorization server supports only `client_secret_post` and exposes no dynamic client registration endpoint, so mcporter's older login flow failed before starting.

The fix adds support for pre-registered OAuth clients. Add these fields to the server entry in your mcporter config:

```jsonc
{
  "mcpServers": {
    "hubspot": {
      "baseUrl": "https://mcp.hubspot.com/mcp",
      "auth": "oauth",
      "oauthClientId": "your-client-id",
      "oauthClientSecretEnv": "HUBSPOT_CLIENT_SECRET",
      "oauthTokenEndpointAuthMethod": "client_secret_post",
      "oauthRedirectUrl": "http://127.0.0.1:3434/callback"
    }
  }
}
```

`oauthClientSecretEnv` points at an environment variable holding the secret; the config also accepts an `oauthClientSecret` field for private local configs. The redirect URL must be allowlisted in the provider app settings — HubSpot's own MCP docs call out adding the client redirect URL when testing with MCP clients.

The maintainer verified against HubSpot's live metadata that no dynamic registration endpoint exists, that `client_secret_post` is advertised, and that with these fields the SDK auth flow now reaches the browser `REDIRECT` step with the configured static client ID instead of failing on DCR. CI passed on macOS, Ubuntu, and Windows for dd33721.

General advice: prefer `oauthClientSecretEnv` over `oauthClientSecret` so the secret never lands in the config file or version control.

AgentArmorHQ team · Answer

**What a GitHub user tried on GitHub** (Didn't work)

Ran `mcporter config login hubspot` against the HubSpot remote MCP server; it failed with "Incompatible auth server: does not support dynamic client registration".

Source: https://github.com/openclaw/mcporter/issues/132

AgentArmorHQ team · Answer

**What @mavam tried on GitHub** (Didn't work)

Added the Slack MCP server with `npx mcporter config add slack https://mcp.slack.com/mcp` then ran `npx mcporter config login slack`; it failed with the same dynamic client registration error.

Source: https://github.com/openclaw/mcporter/issues/132#issuecomment-4174614790

AgentArmorHQ team · Answer

**What @steipete tried on GitHub** (Outcome unclear)

Maintainer checked HubSpot's live OAuth metadata at `/.well-known/oauth-authorization-server`; it advertises only `client_secret_post` and no dynamic registration endpoint, confirming the root cause.

Source: https://github.com/openclaw/mcporter/issues/132#issuecomment-4368725975

AgentArmorHQ team · Answer

**What @steipete tried on GitHub** (Worked)

Maintainer added `oauthClientId`, `oauthClientSecretEnv`, and `oauthTokenEndpointAuthMethod` config support on main (dd33721); a live smoke test reached the redirect step with the static client ID and CI passed on macOS, Ubuntu, and Windows.

Source: https://github.com/openclaw/mcporter/issues/132#issuecomment-4368916262

How to fix mcporter 'Incompatible auth server: does not support dynamic client registration' with HubSpot MCP?

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How to fix mcporter 'Incompatible auth server: does not support dynamic client registration' with HubSpot MCP?

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