diff --git a/package.json b/package.json
index 0143479..e9c934e 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@authsignal/browser",
-  "version": "0.4.2",
+  "version": "0.4.3",
   "type": "module",
   "main": "dist/index.js",
   "module": "dist/index.js",
diff --git a/src/api/passkey-api-client.ts b/src/api/passkey-api-client.ts
index 16f11a9..df0eabb 100644
--- a/src/api/passkey-api-client.ts
+++ b/src/api/passkey-api-client.ts
@@ -3,6 +3,7 @@ import {
   AddAuthenticatorResponse,
   AuthenticationOptsRequest,
   AuthenticationOptsResponse,
+  AuthsignalResponse,
   ChallengeResponse,
   PasskeyAuthenticatorResponse,
   RegistrationOptsRequest,
@@ -29,7 +30,7 @@ export class PasskeyApiClient {
     token,
     username,
     authenticatorAttachment,
-  }: {token: string} & RegistrationOptsRequest): Promise<RegistrationOptsResponse> {
+  }: {token: string} & RegistrationOptsRequest): Promise<AuthsignalResponse<RegistrationOptsResponse>> {
     const body: RegistrationOptsRequest = Boolean(authenticatorAttachment)
       ? {username, authenticatorAttachment}
       : {username};
@@ -46,7 +47,7 @@ export class PasskeyApiClient {
   async authenticationOptions({
     token,
     challengeId,
-  }: {token?: string} & AuthenticationOptsRequest): Promise<AuthenticationOptsResponse> {
+  }: {token?: string} & AuthenticationOptsRequest): Promise<AuthsignalResponse<AuthenticationOptsResponse>> {
     const body: AuthenticationOptsRequest = {challengeId};
 
     const response = fetch(`${this.baseUrl}/client/user-authenticators/passkey/authentication-options`, {
@@ -62,7 +63,7 @@ export class PasskeyApiClient {
     token,
     challengeId,
     registrationCredential,
-  }: {token: string} & AddAuthenticatorRequest): Promise<AddAuthenticatorResponse> {
+  }: {token: string} & AddAuthenticatorRequest): Promise<AuthsignalResponse<AddAuthenticatorResponse>> {
     const body: AddAuthenticatorRequest = {
       challengeId,
       registrationCredential,
@@ -82,7 +83,7 @@ export class PasskeyApiClient {
     challengeId,
     authenticationCredential,
     deviceId,
-  }: {token?: string} & VerifyRequest): Promise<VerifyResponse> {
+  }: {token?: string} & VerifyRequest): Promise<AuthsignalResponse<VerifyResponse>> {
     const body: VerifyRequest = {challengeId, authenticationCredential, deviceId};
 
     const response = fetch(`${this.baseUrl}/client/verify/passkey`, {
@@ -94,7 +95,7 @@ export class PasskeyApiClient {
     return (await response).json();
   }
 
-  async getPasskeyAuthenticator(credentialId: string): Promise<PasskeyAuthenticatorResponse> {
+  async getPasskeyAuthenticator(credentialId: string): Promise<AuthsignalResponse<PasskeyAuthenticatorResponse>> {
     const response = await fetch(`${this.baseUrl}/client/user-authenticators/passkey?credentialId=${credentialId}`, {
       method: "GET",
       headers: this.buildHeaders(),
@@ -107,7 +108,7 @@ export class PasskeyApiClient {
     return response.json();
   }
 
-  async challenge(action: string): Promise<ChallengeResponse> {
+  async challenge(action: string): Promise<AuthsignalResponse<ChallengeResponse>> {
     const response = fetch(`${this.baseUrl}/client/challenge`, {
       method: "POST",
       headers: this.buildHeaders(),
diff --git a/src/api/types.ts b/src/api/types.ts
index e21cc48..10405f0 100644
--- a/src/api/types.ts
+++ b/src/api/types.ts
@@ -54,3 +54,10 @@ export type PasskeyAuthenticatorResponse = {
 export type ChallengeResponse = {
   challengeId: string;
 };
+
+export type ErrorResponse = {
+  error: string;
+  errorDescription?: string;
+};
+
+export type AuthsignalResponse<T> = T | ErrorResponse;
diff --git a/src/helpers.ts b/src/helpers.ts
index 68fa143..605a722 100644
--- a/src/helpers.ts
+++ b/src/helpers.ts
@@ -1,3 +1,5 @@
+import {AuthsignalResponse, ErrorResponse} from "./api/types";
+
 type CookieOptions = {
   name: string;
   value: string;
@@ -6,7 +8,7 @@ type CookieOptions = {
   secure: boolean;
 };
 
-export const setCookie = ({name, value, expire, domain, secure}: CookieOptions): void => {
+export function setCookie({name, value, expire, domain, secure}: CookieOptions) {
   const expireString = expire === Infinity ? " expires=Fri, 31 Dec 9999 23:59:59 GMT" : "; max-age=" + expire;
   document.cookie =
     encodeURIComponent(name) +
@@ -16,13 +18,13 @@ export const setCookie = ({name, value, expire, domain, secure}: CookieOptions):
     expireString +
     (domain ? "; domain=" + domain : "") +
     (secure ? "; secure" : "");
-};
+}
 
-export const getCookieDomain = (): string => {
+export function getCookieDomain() {
   return document.location.hostname.replace("www.", "");
-};
+}
 
-export const getCookie = (name: string) => {
+export function getCookie(name: string) {
   if (!name) {
     return null;
   }
@@ -36,4 +38,8 @@ export const getCookie = (name: string) => {
       )
     ) || null
   );
-};
+}
+
+export function logErrorResponse(errorResponse: ErrorResponse) {
+  console.error(errorResponse.errorDescription ?? errorResponse.error);
+}
diff --git a/src/passkey.ts b/src/passkey.ts
index 709301f..009f415 100644
--- a/src/passkey.ts
+++ b/src/passkey.ts
@@ -2,6 +2,7 @@ import {startAuthentication, startRegistration} from "@simplewebauthn/browser";
 
 import {PasskeyApiClient} from "./api";
 import {AuthenticationResponseJSON, RegistrationResponseJSON, AuthenticatorAttachment} from "@simplewebauthn/types";
+import {logErrorResponse} from "./helpers";
 
 type PasskeyOptions = {
   baseUrl: string;
@@ -28,6 +29,11 @@ export class Passkey {
   async signUp({userName, token, authenticatorAttachment = "platform"}: SignUpParams) {
     const optionsResponse = await this.api.registrationOptions({username: userName, token, authenticatorAttachment});
 
+    if ("error" in optionsResponse) {
+      logErrorResponse(optionsResponse);
+      return;
+    }
+
     const registrationResponse = await startRegistration(optionsResponse.options);
 
     const addAuthenticatorResponse = await this.api.addAuthenticator({
@@ -36,11 +42,16 @@ export class Passkey {
       token,
     });
 
-    if (addAuthenticatorResponse?.isVerified) {
+    if ("error" in addAuthenticatorResponse) {
+      logErrorResponse(addAuthenticatorResponse);
+      return;
+    }
+
+    if (addAuthenticatorResponse.isVerified) {
       this.storeCredentialAgainstDevice(registrationResponse);
     }
 
-    return addAuthenticatorResponse?.accessToken;
+    return addAuthenticatorResponse.accessToken;
   }
 
   async signIn(): Promise<string | undefined>;
@@ -58,11 +69,21 @@ export class Passkey {
 
     const challengeResponse = params?.action ? await this.api.challenge(params.action) : null;
 
+    if (challengeResponse && "error" in challengeResponse) {
+      logErrorResponse(challengeResponse);
+      return;
+    }
+
     const optionsResponse = await this.api.authenticationOptions({
       token: params?.token,
       challengeId: challengeResponse?.challengeId,
     });
 
+    if ("error" in optionsResponse) {
+      logErrorResponse(optionsResponse);
+      return;
+    }
+
     const authenticationResponse = await startAuthentication(optionsResponse.options, params?.autofill);
 
     const verifyResponse = await this.api.verify({
@@ -72,11 +93,16 @@ export class Passkey {
       deviceId: this.anonymousId,
     });
 
-    if (verifyResponse?.isVerified) {
+    if ("error" in verifyResponse) {
+      logErrorResponse(verifyResponse);
+      return;
+    }
+
+    if (verifyResponse.isVerified) {
       this.storeCredentialAgainstDevice(authenticationResponse);
     }
 
-    return verifyResponse?.accessToken;
+    return verifyResponse.accessToken;
   }
 
   async isAvailableOnDevice() {