diff --git a/src/gui/src/UI/UIWindowSignup.js b/src/gui/src/UI/UIWindowSignup.js
index 6f6f8b6dd..f0a4df075 100644
--- a/src/gui/src/UI/UIWindowSignup.js
+++ b/src/gui/src/UI/UIWindowSignup.js
@@ -386,6 +386,22 @@ function UIWindowSignup (options) {
                         // Try to parse error as JSON
                         const errorJson = JSON.parse(errorText);
 
+                        // Handle signup blocked with full-screen overlay
+                        if ( errorJson?.code === 'signup_blocked' ) {
+                            const overlay = document.createElement('div');
+                            overlay.classList.add('signup-blocked-overlay');
+                            const blockedMsg = errorJson.message || 'Signup Not Allowed';
+                            overlay.innerHTML = `
+                                <div class="signup-blocked-content">
+                                    <img src="${window.icons['logo.svg'] || window.icons['logo-white.svg'] || ''}" style="width:64px;margin-bottom:24px;" />
+                                    <p>${html_encode(blockedMsg)}</p>
+                                    <p>If you already have an account, try <a href="/action/login">logging in</a>. Otherwise, contact <a href="mailto:hi@puter.com">hi@puter.com</a> for assistance.</p>
+                                </div>
+                            `;
+                            document.body.appendChild(overlay);
+                            return;
+                        }
+
                         // Handle timeout specifically
                         if ( errorJson?.code === 'response_timeout' || errorText.includes('timeout') ) {
                             $(el_window).find('.signup-error-msg').html(i18n('server_timeout') || 'The server took too long to respond. Please try again.');
diff --git a/src/gui/src/css/style.css b/src/gui/src/css/style.css
index 04dde8a20..4cfcd7815 100644
--- a/src/gui/src/css/style.css
+++ b/src/gui/src/css/style.css
@@ -2072,6 +2072,61 @@ label {
     text-align: left;
 }
 
+.signup-blocked-overlay {
+    position: fixed;
+    top: 0;
+    left: 0;
+    width: 100%;
+    height: 100%;
+    background: #f5f6f8;
+    z-index: 2147483647;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    text-align: center;
+    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
+    color: #1a1a2e;
+}
+
+.signup-blocked-content {
+    padding: 48px 40px;
+    max-width: 460px;
+    display: flex;
+    flex-direction: column;
+    align-items: center;
+    background: #fff;
+    border-radius: 12px;
+    box-shadow: 0 2px 16px rgba(0, 0, 0, 0.08);
+}
+
+.signup-blocked-content h1 {
+    font-size: 22px;
+    font-weight: 600;
+    margin: 0 0 12px 0;
+    color: #1a1a2e;
+}
+
+.signup-blocked-content p {
+    font-size: 14px;
+    line-height: 1.6;
+    margin: 0 0 16px 0;
+    color: #555;
+}
+
+.signup-blocked-content p:last-child {
+    margin-bottom: 0;
+}
+
+.signup-blocked-content a {
+    color: #3a6ff7;
+    text-decoration: none;
+    font-weight: 500;
+}
+
+.signup-blocked-content a:hover {
+    text-decoration: underline;
+}
+
 .error {
     display: none;
     color: red;
diff --git a/src/gui/src/initgui.js b/src/gui/src/initgui.js
index c0d23a197..42c75d931 100644
--- a/src/gui/src/initgui.js
+++ b/src/gui/src/initgui.js
@@ -1323,6 +1323,21 @@ window.initgui = async function (options) {
                                 window.open('', '_self').close();
                             }
                         })();
+                    } else if ( err_obj.code === 'signup_blocked' ) {
+                        // Hide any captcha modal
+                        $('.captcha-modal').hide();
+
+                        const overlay = document.createElement('div');
+                        overlay.classList.add('signup-blocked-overlay');
+                        const blockedMsg = err_obj.message || 'Signup blocked';
+                        overlay.innerHTML = `
+                            <div class="signup-blocked-content">
+                                <img src="${window.icons['logo.svg'] || window.icons['logo-white.svg'] || ''}" style="width:64px;margin-bottom:24px;" />
+                                <p>${html_encode(blockedMsg)}</p>
+                                <p>If you already have an account, try <a href="/action/login">logging in</a>. Otherwise, contact <a href="mailto:hi@puter.com">hi@puter.com</a> for assistance.</p>
+                            </div>
+                        `;
+                        document.body.appendChild(overlay);
                     } else {
                         UIAlert({
                             message: err_obj.message ?? 'There was an error creating your account. Please try again.',