diff --git a/packages/auth-express/src/index.ts b/packages/auth-express/src/index.ts
index e30b699c9..d6e652ebe 100644
--- a/packages/auth-express/src/index.ts
+++ b/packages/auth-express/src/index.ts
@@ -413,7 +413,11 @@ export class ExpressAuth {
         }
         const verifier = req.cookies[this.options.pkceVerifierCookieName];
         if (!verifier) {
-          throw new PKCEError("no pkce verifier cookie found");
+          // End user verified email from a different user agent than sign-up.
+          // This is fine, but the application will need to detect this and
+          // inform the end user that they will need to initiate a new sign up
+          // attempt to complete the flow.
+          return next();
         }
         const isSignUp = searchParams.get("isSignUp") === "true";
         const tokenData = await (await this.core).getToken(code, verifier);
@@ -498,8 +502,13 @@ export class ExpressAuth {
           throw new PKCEError("no verification_token in response");
         }
         if (!verifier) {
-          throw new PKCEError("no pkce verifier cookie found");
+          // End user verified email from a different user agent than sign-up.
+          // This is fine, but the application will need to detect this and
+          // inform the end user that they will need to initiate a new sign up
+          // attempt to complete the flow.
+          return next();
         }
+
         const tokenData = await (
           await this.core
         ).verifyEmailPasswordSignup(verificationToken, verifier);
diff --git a/packages/auth-nextjs/src/shared.ts b/packages/auth-nextjs/src/shared.ts
index e085bcf07..01283dc45 100644
--- a/packages/auth-nextjs/src/shared.ts
+++ b/packages/auth-nextjs/src/shared.ts
@@ -53,7 +53,7 @@ export interface CreateAuthRouteHandlers {
   ): Promise<Response>;
   onEmailVerify(
     params: ParamsOrError<
-      { tokenData: TokenData },
+      { tokenData: TokenData | null },
       { verificationToken?: string }
     >,
     req: NextRequest,
@@ -357,10 +357,14 @@ export abstract class NextAuth extends NextAuthHelpers {
               );
             }
             if (!verifier) {
+              // End user verified email from a different user agent than
+              // sign-up. This is fine, but the application will need to detect
+              // this and inform the end user that they will need to initiate a
+              // new sign up attempt to complete the flow.
               return onEmailVerify(
                 {
-                  error: new PKCEError("no pkce verifier cookie found"),
-                  verificationToken,
+                  error: null,
+                  tokenData: null,
                 },
                 req,
               );
@@ -560,9 +564,16 @@ export abstract class NextAuth extends NextAuthHelpers {
               this.options.pkceVerifierCookieName,
             )?.value;
             if (!verifier) {
+              // End user verified email from a different user agent than
+              // sign-up. This is fine, but the application will need to detect
+              // this and inform the end user that they will need to initiate a
+              // new sign up attempt to complete the flow.
               return onBuiltinUICallback(
                 {
-                  error: new PKCEError("no pkce verifier cookie found"),
+                  error: null,
+                  tokenData: null,
+                  provider: null,
+                  isSignUp: false,
                 },
                 req,
               );
diff --git a/packages/auth-remix/src/server.ts b/packages/auth-remix/src/server.ts
index d55941ccb..32e48686e 100644
--- a/packages/auth-remix/src/server.ts
+++ b/packages/auth-remix/src/server.ts
@@ -86,7 +86,7 @@ export interface CreateAuthRouteHandlers {
   ): Promise<Response>;
   onEmailVerify(
     params: ParamsOrError<
-      { tokenData: TokenData },
+      { tokenData: TokenData | null },
       { verificationToken?: string }
     >,
   ): Promise<Response>;
@@ -358,8 +358,15 @@ export class RemixServerAuth extends RemixClientAuth {
               parseCookies(req)[this.options.pkceVerifierCookieName];
 
             if (!verifier) {
+              // End user verified email from a different user agent than
+              // sign-up. This is fine, but the application will need to detect
+              // this and inform the end user that they will need to initiate a
+              // new sign up attempt to complete the flow.
               return cbCall(onBuiltinUICallback, {
-                error: new PKCEError("no pkce verifier cookie found"),
+                error: null,
+                tokenData: null,
+                provider: null,
+                isSignUp: false,
               });
             }
             const isSignUp = searchParams.get("isSignUp") === "true";
@@ -422,9 +429,13 @@ export class RemixServerAuth extends RemixClientAuth {
               });
             }
             if (!verifier) {
+              // End user verified email from a different user agent than
+              // sign-up. This is fine, but the application will need to detect
+              // this and inform the end user that they will need to initiate a
+              // new sign up attempt to complete the flow.
               return cbCall(onEmailVerify, {
-                error: new PKCEError("no pkce verifier cookie found"),
-                verificationToken,
+                error: null,
+                tokenData: null,
               });
             }
             let tokenData: TokenData;
diff --git a/packages/auth-sveltekit/src/server.ts b/packages/auth-sveltekit/src/server.ts
index 253e98c1d..b35ed0517 100644
--- a/packages/auth-sveltekit/src/server.ts
+++ b/packages/auth-sveltekit/src/server.ts
@@ -63,7 +63,7 @@ export interface AuthRouteHandlers {
   ) => Promise<never>;
   onEmailVerify?: (
     params: ParamsOrError<
-      { tokenData: TokenData },
+      { tokenData: TokenData | null },
       { verificationToken?: string }
     >,
   ) => Promise<never>;
@@ -597,8 +597,15 @@ async function handleAuthRoutes(
       const verifier = cookies.get(config.pkceVerifierCookieName);
 
       if (!verifier) {
+        // End user verified email from a different user agent than sign-up.
+        // This is fine, but the application will need to detect this and inform
+        // the end user that they will need to initiate a new sign up attempt to
+        // complete the flow.
         return onBuiltinUICallback({
-          error: new PKCEError("no pkce verifier cookie found"),
+          error: null,
+          tokenData: null,
+          provider: null,
+          isSignUp: false,
         });
       }
       const isSignUp = searchParams.get("isSignUp") === "true";
@@ -653,9 +660,13 @@ async function handleAuthRoutes(
         });
       }
       if (!verifier) {
+        // End user verified email from a different user agent than sign-up.
+        // This is fine, but the application will need to detect this and inform
+        // the end user that they will need to initiate a new sign up attempt to
+        // complete the flow.
         return onEmailVerify({
-          error: new PKCEError("no pkce verifier cookie found"),
-          verificationToken,
+          error: null,
+          tokenData: null,
         });
       }
       let tokenData: TokenData;