What causes "Unable to generate token" in gofr-dev/gofr?

Check the form/body the client sends to the token URL matches what getClaims expects (grant_type, client_id, etc.).

Unable to generate token

Error message

Unable to generate token

What it means

In mock_oauth_server.go:63, if the mock server's generateToken (signing/claims marshalling) returns an error, the token endpoint responds with a 500 and the body "Unable to generate token". This is a server-side failure inside the test double, meaning credentials were accepted but token creation failed.

Source

Thrown at pkg/gofr/service/mock_oauth_server.go:63

	privateKey, err := rsa.GenerateKey(rand.Reader, privateKeyBits)
	require.NoError(t, err, "failed to generate private key, aborting")

	server.privateKey = privateKey

	mux := http.NewServeMux()

	mux.HandleFunc(server.tokenURL, func(w http.ResponseWriter, r *http.Request) {
		errMessage, statusCode := server.validateCredentials(r)

		if statusCode != http.StatusOK {
			http.Error(w, errMessage, statusCode)
			return
		}

		accessToken, err := server.generateToken(getClaims(r))
		if err != nil {
			http.Error(w, "Unable to generate token", http.StatusInternalServerError)
			return
		}

		// Prepare the JSON response
		w.Header().Set("Content-Type", "application/json")
		w.Header().Set("Cache-Control", "no-store")
		w.Header().Set("Pragma", "no-cache")

		tokenResponse := map[string]any{
			"access_token": accessToken,
			"token_type":   "Bearer",
			"expires_in":   3600,         // Expires in 1 hour
			"scope":        "read write", // Mock scope
		}

		_ = json.NewEncoder(w).Encode(tokenResponse)
	})

View on GitHub (pinned to 187eb24962)

Solutions

Check the form/body the client sends to the token URL matches what getClaims expects (grant_type, client_id, etc.).
Verify server.tokenURL registration matches the path the client requests, so only well-formed requests reach this handler.
Inspect generateToken for signing-key configuration errors in the test setup.
Update the mock's getClaims/generateToken to support the new request shape if your client legitimately changed.

Defensive patterns

Strategy: try-catch

Validate before calling

// send the exact form the mock expects
form := url.Values{"grant_type": {"client_credentials"}, "client_id": {id}, "client_secret": {secret}}
if form.Get("grant_type") == "" { return errors.New("grant_type required by mock getClaims") }

Try / catch

if resp.StatusCode == http.StatusInternalServerError && strings.Contains(body, "Unable to generate token") {
	return fmt.Errorf("mock server could not build token from request claims; check getClaims expectations: %s", body)
}

Prevention

Match the token request encoding (form fields) to what the mock's getClaims parses.
Keep server.tokenURL and the client's token URL identical in test fixtures.
Pin the mock server implementation in your test helpers to avoid drift.
Log request bodies in the mock when generateToken fails.

When it happens

Trigger: POST to the mock token URL with valid credentials, but generateToken(getClaims(r)) fails — typically because getClaims produced malformed/unparseable claims (e.g. unsupported grant_type or a body shape the claims extractor cannot handle) or the signing step errors.

Common situations: Sending a client_credentials request when the mock only expects a specific form encoding; test helper changes to getClaims breaking compatibility; misconfigured token URL causing requests to hit the handler with an unexpected request shape.

Related errors

AI-assisted analysis of gofr-dev/gofr@187eb24962 (2026-09-01). Data as JSON: /api/errors/271c015f2482c692. Report an issue: GitHub.